Azure Communication Services Email API for GA (Azure#22979)

* Copy existing preview version of CommunicationServicesEmail API to stable folder in preparation for GA

* update version to 2023-03-31

* update comment about events for 202 result

* update readme file

* updated description of Operation-ID header

Author: apattath

specification/communication/data-plane/Email/readme.md

@@ -26,7 +26,7 @@ These are the global settings for the communicationservices.
 
 ```yaml
 openapi-type: data-plane
-tag: package-2023-01-15-preview
+tag: package-2023-03-31
 ```
 
 ### Tag: package-2021-10-01-preview
@@ -51,6 +51,17 @@ title:
   Azure Communication Services
 ```
 
+### Tag: package-2023-03-31
+
+These settings apply only when `--tag=package-2023-03-31` is specified on the command line.
+
+```yaml $(tag) == 'package-2023-03-31'
+input-file:
+  - stable/2023-03-31/CommunicationServicesEmail.json
+title:
+  Azure Communication Services
+```
+
 ---
 
 # Code Generation