Document GithubService autoconfiguration on import

doc/user/project/import/github.md

@@ -126,6 +126,12 @@ If you want, you can import all your GitHub projects in one go by hitting
 You can also choose a different name for the project and a different namespace,
 if you have the privileges to do so.
 
+## Mirroring
+
+[Project mirroring](../../../workflow/repository_mirroring.md) can be set up to keep your imported project in sync. Additionally you can configure GitLab to send pipeline status updates back GitHub with the [GitHub Project Integration](../integrations/github.md).
+
+If you import you project using "CI/CD for external repo" then both of the above will be automatically configured.
+
 ## Making the import process go faster
 
 For large projects it may take a while to import all data. To reduce the time

doc/user/project/integrations/github.md

@@ -2,6 +2,8 @@
 
 GitLab provides integration for updating pipeline statuses on GitHub. This is especially useful if using GitLab for CI/CD only.
 
+This project integration is separate from the [instance wide GitHub integration][gh-integration] and is automatically configured on [GitHub import][gh-import].
+
 ![Pipeline status update on GitHub](img/github_status_check_pipeline_update.png)
 
 ## Configuration
@@ -28,3 +30,5 @@ This integration requires a [GitHub API token](https://github.com/settings/token
 
 ![Configure GitHub Project Integration](img/github_configuration.png)
 
+[gh-import]: ../import/github.md#mirroring
+[gh-integration]: ../../../integration/github.md

ee/app/views/projects/_new_ci_cd_only_project_pane.html.haml

@@ -8,6 +8,9 @@
           = _('Run CI/CD pipelines for external repositories')
         %p
           = _('Connect your external repositories, and CI/CD pipelines will run for new commits. A GitLab project will be created with only CI/CD features enabled.')
+        %p
+          - more_info_link = link_to _('More info'), help_page_path('user/project/integrations/github')
+          = _('If using GitHub, you’ll see pipeline statuses on GitHub for your commits and pull requests. %{more_info_link}').html_safe % { more_info_link: more_info_link }
 
         .form-group.import-btn-container.prepend-top-20.clearfix
           = f.label :visibility_level, class: 'label-light' do