[docs] Fix subversion.py export example (#60438)

The svn export example was missing the `export: yes` parameter. It was accidentally omitted when the syntax was changed in ad6999e2eb.

lib/ansible/modules/source_control/subversion.py

@@ -98,6 +98,7 @@ EXAMPLES = '''
   subversion:
     repo: svn+ssh://an.example.org/path/to/repo
     dest: /src/export
+    export: yes
 
 - name: Get information about the repository whether or not it has already been cloned locally
 - subversion: