Peering: update java readme (#7329)

Author: ChenTanyi

specification/peering/resource-manager/readme.java.md

@@ -4,11 +4,30 @@ These settings apply only when `--java` is specified on the command line.
 Please also specify `--azure-libraries-for-java-folder=<path to the root directory of your azure-libraries-for-java clone>`.
 
 ``` yaml $(java)
-java:
-  azure-arm: true
-  fluent: true
-  namespace: com.microsoft.azure.management.peering
-  license-header: MICROSOFT_MIT_NO_CODEGEN
-  payload-flattening-threshold: 1
-  output-folder: $(azure-libraries-for-java-folder)/azure-mgmt-peering
+azure-arm: true
+fluent: true
+namespace: com.microsoft.azure.management.peering
+license-header: MICROSOFT_MIT_NO_CODEGEN
+payload-flattening-threshold: 1
+output-folder: $(azure-libraries-for-java-folder)/azure-mgmt-peering
+```
+
+### Java multi-api
+
+``` yaml $(java) && $(multiapi)
+batch:
+  - tag: package-2019-08-01-preview
 ```
+
+### Tag: package-2019-08-01-preview and java
+
+These settings apply only when `--tag=package-2019-08-01-preview --java` is specified on the command line.
+Please also specify `--azure-libraries-for-java=<path to the root directory of your azure-sdk-for-java clone>`.
+
+``` yaml $(tag) == 'package-2019-08-01-preview' && $(java) && $(multiapi)
+java:
+  namespace: com.microsoft.azure.management.peering.v2019_08_01_preview
+  output-folder: $(azure-libraries-for-java-folder)/peering/resource-manager/v2019_08_01_preview
+regenerate-manager: true
+generate-interface: true
+```