Update readme.md (Azure#19325)

Author: kagbakpem

specification/communication/resource-manager/readme.md

@@ -28,7 +28,7 @@ These are the global settings for the Azure Communication Services API.
 title: CommunicationServiceManagementClient
 openapi-type: arm
 openapi-subtype: rpaas
-tag: package-2020-08-20
+tag: package-2021-10-01-preview
 ```
 
 ### Tag: package-2020-08-20
@@ -99,4 +99,4 @@ See configuration in [readme.typescript.md](./readme.typescript.md)
 
 ## Comments and notes
 x-ms-identifiers will become a requirement on every RP resource. To add it, [check here](https://github.com/Azure/autorest/tree/main/docs/extensions#x-ms-identifiers).
-For more info, reach out to the @changeanalysisteam.
+For more info, reach out to the @changeanalysisteam.