doc: Adds documentation about instance_size in electable_specs (#3168)

* typos

* electable_specs doc

* revert test

* read_only_specs

Author: lantoli

docs/data-sources/advanced_cluster (preview provider 2.0.0).md

@@ -181,7 +181,7 @@ Key-value pairs that categorize the cluster. Each key and value has a maximum le
 * `id` - **(DEPRECATED)** Unique identifer of the replication document for a zone in a Global Cluster. This value corresponds to the legacy sharding schema (no independent shard scaling) and is different from the Shard ID you may see in the Atlas UI. This value is not populated (empty string) when a sharded cluster has independently scaled shards.
 * `external_id` - Unique 24-hexadecimal digit string that identifies the replication object for a shard in a Cluster. This value corresponds to Shard ID displayed in the UI. When using old sharding configuration (replication spec with `num_shards` greater than 1) this value is not populated.
 * `num_shards` - Provide this value if you set a `cluster_type` of `SHARDED` or `GEOSHARDED`. **(DEPRECATED)** To learn more, see the [Migration Guide](../guides/1.18.0-upgrade-guide.html.markdown).
-* `region_configs` - Configuration for the hardware specifications for nodes set for a given regionEach `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs)
+* `region_configs` - Configuration for the hardware specifications for nodes set for a given region. Each `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs).
 *  `container_id` - A key-value map of the Network Peering Container ID(s) for the configuration specified in `region_configs`. The Container ID is the id of the container either created programmatically by the user before any clusters existed in a project or when the first cluster in the region (AWS/Azure) or project (GCP) was created.  The syntax is `"providerName:regionName" = "containerId"`. Example `AWS:US_EAST_1" = "61e0797dde08fb498ca11a71`.
 * `zone_name` - Name for the zone in a Global Cluster.
 * `zone_id` - Unique 24-hexadecimal digit string that identifies the zone in a Global Cluster. If clusterType is GEOSHARDED, this value indicates the zone that the given shard belongs to and can be used to configure Global Cluster backup policies.

docs/data-sources/advanced_cluster.md

@@ -168,7 +168,7 @@ Key-value pairs that categorize the cluster. Each key and value has a maximum le
 * `id` - **(DEPRECATED)** Unique identifer of the replication document for a zone in a Global Cluster. This value corresponds to the legacy sharding schema (no independent shard scaling) and is different from the Shard ID you may see in the Atlas UI. This value is not populated (empty string) when a sharded cluster has independently scaled shards.
 * `external_id` - Unique 24-hexadecimal digit string that identifies the replication object for a shard in a Cluster. This value corresponds to Shard ID displayed in the UI. When using old sharding configuration (replication spec with `num_shards` greater than 1) this value is not populated.
 * `num_shards` - Provide this value if you set a `cluster_type` of `SHARDED` or `GEOSHARDED`. **(DEPRECATED)** To learn more, see the [Migration Guide](../guides/1.18.0-upgrade-guide.html.markdown).
-* `region_configs` - Configuration for the hardware specifications for nodes set for a given regionEach `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs)
+* `region_configs` - Configuration for the hardware specifications for nodes set for a given region. Each `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs).
 *  `container_id` - A key-value map of the Network Peering Container ID(s) for the configuration specified in `region_configs`. The Container ID is the id of the container either created programmatically by the user before any clusters existed in a project or when the first cluster in the region (AWS/Azure) or project (GCP) was created.  The syntax is `"providerName:regionName" = "containerId"`. Example `AWS:US_EAST_1" = "61e0797dde08fb498ca11a71`.
 * `zone_name` - Name for the zone in a Global Cluster.
 * `zone_id` - Unique 24-hexadecimal digit string that identifies the zone in a Global Cluster. If clusterType is GEOSHARDED, this value indicates the zone that the given shard belongs to and can be used to configure Global Cluster backup policies.

docs/data-sources/advanced_clusters (preview provider 2.0.0).md

@@ -179,7 +179,7 @@ Key-value pairs that categorize the cluster. Each key and value has a maximum le
 * `id` - **(DEPRECATED)** Unique identifer of the replication document for a zone in a Global Cluster. This value corresponds to the legacy sharding schema (no independent shard scaling) and is different from the Shard ID you may see in the Atlas UI. This value is not populated (empty string) when a sharded cluster has independently scaled shards.
 * `external_id` - Unique 24-hexadecimal digit string that identifies the replication object for a shard in a Cluster. This value corresponds to Shard ID displayed in the UI. When using old sharding configuration (replication spec with `num_shards` greater than 1) this value is not populated.
 * `num_shards` - Provide this value if you set a `cluster_type` of SHARDED or GEOSHARDED. **(DEPRECATED)** To learn more, see the [Migration Guide](../guides/1.18.0-upgrade-guide.html.markdown) for more details.
-* `region_configs` - Configuration for the hardware specifications for nodes set for a given regionEach `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs)
+* `region_configs` - Configuration for the hardware specifications for nodes set for a given region. Each `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs).
 *  `container_id` - A key-value map of the Network Peering Container ID(s) for the configuration specified in `region_configs`. The Container ID is the id of the container either created programmatically by the user before any clusters existed in a project or when the first cluster in the region (AWS/Azure) or project (GCP) was created.  The syntax is `"providerName:regionName" = "containerId"`. Example `AWS:US_EAST_1" = "61e0797dde08fb498ca11a71`.
 * `zone_name` - Name for the zone in a Global Cluster.
 * `zone_id` - Unique 24-hexadecimal digit string that identifies the zone in a Global Cluster. If clusterType is GEOSHARDED, this value indicates the zone that the given shard belongs to and can be used to configure Global Cluster backup policies.

docs/data-sources/advanced_clusters.md

@@ -169,7 +169,7 @@ Key-value pairs that categorize the cluster. Each key and value has a maximum le
 * `id` - **(DEPRECATED)** Unique identifer of the replication document for a zone in a Global Cluster. This value corresponds to the legacy sharding schema (no independent shard scaling) and is different from the Shard ID you may see in the Atlas UI. This value is not populated (empty string) when a sharded cluster has independently scaled shards.
 * `external_id` - Unique 24-hexadecimal digit string that identifies the replication object for a shard in a Cluster. This value corresponds to Shard ID displayed in the UI. When using old sharding configuration (replication spec with `num_shards` greater than 1) this value is not populated.
 * `num_shards` - Provide this value if you set a `cluster_type` of SHARDED or GEOSHARDED. **(DEPRECATED)** To learn more, see the [Migration Guide](../guides/1.18.0-upgrade-guide.html.markdown) for more details.
-* `region_configs` - Configuration for the hardware specifications for nodes set for a given regionEach `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs)
+* `region_configs` - Configuration for the hardware specifications for nodes set for a given region. Each `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs).
 *  `container_id` - A key-value map of the Network Peering Container ID(s) for the configuration specified in `region_configs`. The Container ID is the id of the container either created programmatically by the user before any clusters existed in a project or when the first cluster in the region (AWS/Azure) or project (GCP) was created.  The syntax is `"providerName:regionName" = "containerId"`. Example `AWS:US_EAST_1" = "61e0797dde08fb498ca11a71`.
 * `zone_name` - Name for the zone in a Global Cluster.
 * `zone_id` - Unique 24-hexadecimal digit string that identifies the zone in a Global Cluster. If clusterType is GEOSHARDED, this value indicates the zone that the given shard belongs to and can be used to configure Global Cluster backup policies.

docs/resources/advanced_cluster (preview provider 2.0.0).md

@@ -768,7 +768,7 @@ replication_specs = [
 * `external_id` - Unique 24-hexadecimal digit string that identifies the replication object for a shard in a Cluster. This value corresponds to Shard ID displayed in the UI. When using old sharding configuration (replication spec with `num_shards` greater than 1) this value is not populated.
 * `num_shards` - (Optional) Provide this value if you set a `cluster_type` of SHARDED or GEOSHARDED. Omit this value if you selected a `cluster_type` of REPLICASET. This API resource accepts 1 through 50, inclusive. This parameter defaults to 1. If you specify a `num_shards` value of 1 and a `cluster_type` of SHARDED, Atlas deploys a single-shard [sharded cluster](https://docs.atlas.mongodb.com/reference/glossary/#std-term-sharded-cluster). Don't create a sharded cluster with a single shard for production environments. Single-shard sharded clusters don't provide the same benefits as multi-shard configurations.
 If you are upgrading a replica set to a sharded cluster, you cannot increase the number of shards in the same update request. You should wait until after the cluster has completed upgrading to sharded and you have reconnected all application clients to the MongoDB router before adding additional shards. Otherwise, your data might become inconsistent once MongoDB Cloud begins distributing data across shards. To learn more, see [Convert a replica set to a sharded cluster documentation](https://www.mongodb.com/docs/atlas/scale-cluster/#convert-a-replica-set-to-a-sharded-cluster) and [Convert a replica set to a sharded cluster tutorial](https://www.mongodb.com/docs/upcoming/tutorial/convert-replica-set-to-replicated-shard-cluster). **(DEPRECATED)** To learn more, see the [1.18.0 Upgrade Guide](../guides/1.18.0-upgrade-guide.html.markdown).
-* `region_configs` - (Optional) Configuration for the hardware specifications for nodes set for a given regionEach `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs)
+* `region_configs` - (Optional) Configuration for the hardware specifications for nodes set for a given region. Each `region_configs` object describes the region's priority in elections and the number and type of MongoDB nodes that Atlas deploys to the region. Each `region_configs` object must have either an `analytics_specs` object, `electable_specs` object, or `read_only_specs` object. See [below](#region_configs).
 * `zone_name` - (Optional) Name for the zone in a Global Cluster.
 * `zone_id` - Unique 24-hexadecimal digit string that identifies the zone in a Global Cluster. If clusterType is GEOSHARDED, this value indicates the zone that the given shard belongs to and can be used to configure Global Cluster backup policies.
 
@@ -779,18 +779,17 @@ If you are upgrading a replica set to a sharded cluster, you cannot increase the
 * `auto_scaling` - (Optional) Configuration for the collection of settings that configures auto-scaling information for the cluster. The values for the `auto_scaling` attribute must be the same for all `region_configs` of a cluster. See [below](#auto_scaling).
 * `analytics_auto_scaling` - (Optional) Configuration for the Collection of settings that configures analytics-auto-scaling information for the cluster. The values for the `analytics_auto_scaling` attribute must be the same for all `region_configs` of a cluster. See [below](#analytics_auto_scaling).
 * `backing_provider_name` - (Optional) Cloud service provider on which you provision the host for a multi-tenant cluster. Use this only when a `provider_name` is `TENANT` and `instance_size` is `M0`.
-* `electable_specs` - (Optional) Hardware specifications for electable nodes in the region. Electable nodes can become the [primary](https://docs.atlas.mongodb.com/reference/glossary/#std-term-primary) and can enable local reads. If you do not specify this option, no electable nodes are deployed to the region. See [below](#specs).
+* `electable_specs` - (Optional) Hardware specifications for electable nodes in the region. All `electable_specs` in the `region_configs` of a `replication_specs` must have the same `instance_size`. Electable nodes can become the [primary](https://docs.atlas.mongodb.com/reference/glossary/#std-term-primary) and can enable local reads. If you do not specify this option, no electable nodes are deployed to the region. See [below](#specs).
 * `priority` - (Optional)  Election priority of the region. For regions with only read-only nodes, set this value to 0.
   * If you have multiple `region_configs` objects (your cluster is multi-region or multi-cloud), they must have priorities in descending order. The highest priority is 7.
   * If your region has set `region_configs[#].electable_specs.node_count` to 1 or higher, it must have a priority of exactly one (1) less than another region in the `replication_specs[#].region_configs[#]` array. The highest-priority region must have a priority of 7. The lowest possible priority is 1.
 * `provider_name` - (Optional) Cloud service provider on which the servers are provisioned.
   The possible values are:
-
   - `AWS` - Amazon AWS
   - `GCP` - Google Cloud Platform
   - `AZURE` - Microsoft Azure
   - `TENANT` - M0 multi-tenant cluster. Use `replication_specs.[#].region_configs[#].backing_provider_name` to set the cloud service provider.
-* `read_only_specs` - (Optional) Hardware specifications for read-only nodes in the region. Read-only nodes can become the [primary](https://docs.atlas.mongodb.com/reference/glossary/#std-term-primary) and can enable local reads. If you don't specify this parameter, no read-only nodes are deployed to the region. See [below](#specs).
+* `read_only_specs` - (Optional) Hardware specifications for read-only nodes in the region. All `read_only_specs` in the `region_configs` of a `replication_specs` must have the same `instance_size` as `electable_specs`. Read-only nodes can become the [primary](https://docs.atlas.mongodb.com/reference/glossary/#std-term-primary) and can enable local reads. If you don't specify this parameter, no read-only nodes are deployed to the region. See [below](#specs).
 * `region_name` - (Optional) Physical location of your MongoDB cluster. The region you choose can affect network latency for clients accessing your databases.  Requires the **Atlas region name**, see the reference list for [AWS](https://docs.atlas.mongodb.com/reference/amazon-aws/), [GCP](https://docs.atlas.mongodb.com/reference/google-gcp/), [Azure](https://docs.atlas.mongodb.com/reference/microsoft-azure/).
 
 ### electable_specs