Add edit URI and icon.

mkdocs.yml

 site_name: 'CiviCRM User Guide'
 site_url: https://docs.civicrm.org/user/en/stable/
-repo_url: https://github.com/civicrm/civicrm-user-guide
+repo_url: https://lab.civicrm.org/documentation/docs/user-en/
+edit_uri: https://lab.civicrm.org/-/ide/project/documentation/docs/user-en/tree/master/-/docs/
 site_description: 'A guide for CiviCRM users.'
 site_author: 'The CiviCRM community'
 theme: 
   name: material
+  icon:
+      repo: fontawesome/brands/gitlab
 
 markdown_extensions:
   - attr_list