Merge branch 'access-levels-docs' into 'master'

Documentation: added missing } in a json example

See merge request gitlab-org/gitlab-ee!10497

doc/api/protected_branches.md

@@ -181,6 +181,7 @@ Example response:
       "user_id":null,
       "group_id":null,
       "access_level_description":"Maintainers"
+    }
   ],
   "unprotect_access_levels": [
     {