Fix documentation for Alloydb Instance availability_type (#8172) (#5792)

Signed-off-by: Modular Magician <[email protected]>
Co-authored-by: Riley Karson <[email protected]>

Author: modular-magician

.changelog/8172.txt

@@ -0,0 +1,3 @@
+```release-note:none
+Fix documentation for Alloydb Instance availability_type
+```

google-beta/services/alloydb/resource_alloydb_instance.go

@@ -81,7 +81,12 @@ func ResourceAlloydbInstance() *schema.Resource {
 				Computed:     true,
 				Optional:     true,
 				ValidateFunc: verify.ValidateEnum([]string{"AVAILABILITY_TYPE_UNSPECIFIED", "ZONAL", "REGIONAL", ""}),
-				Description:  `Availability type of an Instance. Defaults to REGIONAL for both primary and read instances. Note that primary and read instances can have different availability types. Possible values: ["AVAILABILITY_TYPE_UNSPECIFIED", "ZONAL", "REGIONAL"]`,
+				Description: `'Availability type of an Instance. Defaults to REGIONAL for both primary and read instances.
+Note that primary and read instances can have different availability types.
+Only READ_POOL instance supports ZONAL type. Users can't specify the zone for READ_POOL instance.
+Zone is automatically chosen from the list of zones in the region specified.
+Read pool of size 1 can only have zonal availability. Read pools with node count of 2 or more
+can have regional availability (nodes are present in 2 or more zones in a region).' Possible values: ["AVAILABILITY_TYPE_UNSPECIFIED", "ZONAL", "REGIONAL"]`,
 			},
 			"database_flags": {
 				Type:        schema.TypeMap,

website/docs/r/alloydb_instance.html.markdown

@@ -125,7 +125,12 @@ The following arguments are supported:
 
 * `availability_type` -
   (Optional)
-  Availability type of an Instance. Defaults to REGIONAL for both primary and read instances. Note that primary and read instances can have different availability types.
+  'Availability type of an Instance. Defaults to REGIONAL for both primary and read instances.
+  Note that primary and read instances can have different availability types.
+  Only READ_POOL instance supports ZONAL type. Users can't specify the zone for READ_POOL instance.
+  Zone is automatically chosen from the list of zones in the region specified.
+  Read pool of size 1 can only have zonal availability. Read pools with node count of 2 or more
+  can have regional availability (nodes are present in 2 or more zones in a region).'
   Possible values are: `AVAILABILITY_TYPE_UNSPECIFIED`, `ZONAL`, `REGIONAL`.
 
 * `read_pool_config` -