update readme.java.md (#10594)

Author: xseeseesee

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

@@ -18,6 +18,7 @@ service-name: MariaDB
 ``` yaml $(java) && $(multiapi)
 batch:
   - tag: package-2018-06-01
+  - tag: package-2020-01-01  
 ```
 
 ### Tag: package-2018-06-01 and java
@@ -32,3 +33,16 @@ java:
 regenerate-manager: true
 generate-interface: true
 ```
+
+### Tag: package-2020-01-01 and java
+
+These settings apply only when `--tag=package-2020-01-01 --java` is specified on the command line.
+Please also specify `--azure-libraries-for-java-folder=<path to the root directory of your azure-sdk-for-java clone>`.
+
+``` yaml $(tag) == 'package-2020-01-01' && $(java) && $(multiapi)
+java:
+  namespace: com.microsoft.azure.management.mariadb.v2020_01_01
+  output-folder: $(azure-libraries-for-java-folder)/sdk/mariadb/mgmt-v2020_01_01
+regenerate-manager: true
+generate-interface: true
+```