add new version tag for mysql (#28886)

Author: kazrael2119

specification/mysql/resource-manager/readme.typescript.md

@@ -9,6 +9,17 @@ typescript:
   generate-metadata: true
 ```
 
+### Tag: package-flexibleserver-2023-12-30 and TypeScript
+
+These settings apply only when `--tag=package-flexibleserver-2023-12-30 --typescript` is specified on the command line.
+Please also specify `--typescript-sdks-folder=<path to the root directory of your azure-sdk-for-typescript clone>`.
+
+``` yaml $(tag) == 'package-flexibleserver-2023-12-30' && $(typescript)
+title: MySQLManagementFlexibleServerClient
+package-name: "@azure/arm-mysql-flexible"
+output-folder: "$(typescript-sdks-folder)/sdk/mysql/arm-mysql-flexible/"
+```
+
 ### Tag: package-flexibleserver-2021-05-01 and TypeScript
 
 These settings apply only when `--tag=package-flexibleserver-2021-05-01 --typescript` is specified on the command line.