[DOCS] Improve number_of_shards option page

docs/reference/option_number_of_shards.md

@@ -1,15 +1,35 @@
 ---
 mapped_pages:
   - https://www.elastic.co/guide/en/elasticsearch/client/curator/current/option_number_of_shards.html
+applies_to:
+  stack: both
+  serverless: unavailable
+products:
+  - id: elasticsearch
 ---
 
 # number_of_shards [option_number_of_shards]
 
+The `number_of_shards` option specifies the number of primary shards in the target index created by the shrink action.
+
 ::::{note}
-This setting is only used by the [shrink](/reference/shrink.md) action.
+`number_of_shards` is used only by the [shrink](/reference/shrink.md) action.
 ::::
 
+* **Type:** Integer
+* **Required:** Optional
+* **Required:** Optional
+
+The value of `number_of_shards` determines the number of primary shards in the target index after the shrink operation.
+
+::::{important}
+The value of `number_of_shards` must meet the following criteria:
+* It must be lower than the number of primary shards in the source index.
+* It must be a factor of the number of primary shards in the source index.
 
+For example, a source index with 8 primary shards can be shrunk to 4, 2, or 1, and cannot be shrunk to 3 or 5.
+::::
+
 ```yaml
 action: shrink
 description: >-
@@ -22,14 +42,10 @@
   - filtertype: ...
 ```
 
-The value of this setting determines the number of primary shards in the target index.  The default value is `1`.
-
-::::{important}
-The value for `number_of_shards` must meet the following criteria:
+Before you use `number_of_shards`, learn about shards and how shard count and sizing affect performance and scalability. For details, check the following:
 
-* It must be lower than the number of primary shards in the source index.
-* It must be a factor of the number of primary shards in the source index.
+* [Clusters, nodes, and shards](docs-content://deploy-manage/distributed-architecture/clusters-nodes-shards.md)
+* [Size your shards](docs-content://deploy-manage/production-guidance/optimize-performance/size-shards.md)
 
-::::