[MM-62398] Fix /api/v4/reports/users/export api docs (#29750)

api/v4/source/introduction.yaml

@@ -613,6 +613,7 @@ x-tagGroups:
       - permissions
       - exports
       - usage
+      - reports
 servers:
   - url: http://your-mattermost-url.com
   - url: https://your-mattermost-url.com