Document forking restriction in project settings

doc/user/project/settings/index.md

@@ -43,6 +43,7 @@ Use the switches to enable or disable the following features:
 | **Issues**                        | ✓                         | Activates the GitLab issues tracker                                                                                                                                                            |
 | **Repository**                    | ✓                         | Enables [repository](../repository/) functionality                                                                                                                                             |
 | **Merge Requests**                | ✓                         | Enables [merge request](../merge_requests/) functionality; also see [Merge request settings](#merge-request-settings)                                                                          |
+| **Forks**                         | ✓                         | Enables [forking](../index.md#fork-a-project) functionality                                                                                                                                    |
 | **Pipelines**                     | ✓                         | Enables [CI/CD](../../../ci/README.md) functionality                                                                                                                                           |
 | **Container Registry**            |                           | Activates a [registry](../../packages/container_registry/) for your docker images                                                                                                              |
 | **Git Large File Storage**        |                           | Enables the use of [large files](../../../administration/lfs/manage_large_binaries_with_git_lfs.md#git-lfs)                                                                                    |