{rdbms} Fix #17579: Add document reference where updated versions are…

… available (#23463)

* {rdbms} Fix #17579: Add document reference where updated versions are available

Fixes #17579

* {rdbms} Fix #17579: Implement PR review change

* {rdbms} Fix Azure#17579: Implement PR review change

* {rdbms} Fix #17579: Implement PR changes

* {rdbms} Fix Azure#17579: Implement PR changes

src/azure-cli/azure/cli/command_modules/rdbms/_params.py

@@ -89,7 +89,11 @@ def _complex_params(command_group):  # pylint: disable=too-many-statements
             c.argument('assign_identity', options_list=['--assign-identity'], help='Generate and assign an Azure Active Directory Identity for this server for use with key management services like Azure KeyVault.')
 
             c.argument('location', arg_type=get_location_type(self.cli_ctx))
-            c.argument('version', help='Server major version.')
+            if command_group == 'postgres':
+                c.argument('version', default='11',
+                           help='Server major version. https://docs.microsoft.com/en-us/azure/postgresql/single-server/concepts-supported-versions')
+            else:
+                c.argument('version', help='Server major version.')
 
         with self.argument_context('{} server update'.format(command_group)) as c:
             c.ignore('family', 'capacity', 'tier')