Resolve "Push option `merge_request.create` does not work for forks"

doc/user/project/push_options.md

@@ -61,7 +61,7 @@ time as pushing changes:
 | Push option                                  | Description                                                                                                     | Introduced in version |
 | -------------------------------------------- | --------------------------------------------------------------------------------------------------------------- | --------------------- |
 | `merge_request.create`                       | Create a new merge request for the pushed branch.                                                               | [11.10](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/26752) |
-| `merge_request.target=<branch_name>`         | Set the target of the merge request to a particular branch.                                                     | [11.10](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/26752) |
+| `merge_request.target=<branch_name>`         | Set the target of the merge request to a particular branch or upstream project, such as: `git push -o merge_request.target=project_path/branch`                                                     | [11.10](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/26752) |
 | `merge_request.merge_when_pipeline_succeeds` | Set the merge request to [merge when its pipeline succeeds](merge_requests/merge_when_pipeline_succeeds.md).    | [11.10](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/26752) |
 | `merge_request.remove_source_branch`         | Set the merge request to remove the source branch when it's merged.                                             | [12.2](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/64320)          |
 | `merge_request.title="<title>"`              | Set the title of the merge request. Ex: `git push -o merge_request.title="The title I want"`.                   | [12.2](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/64320)          |