doc: make external link explicit

Author: story645

doc/devel/development_setup.rst

@@ -119,8 +119,8 @@ code, as described in :ref:`development-workflow`.
    * `GitHub-Contributing to a Project
      <https://git-scm.com/book/en/v2/GitHub-Contributing-to-a-Project>`_
    * `GitHub Skills <https://skills.github.com/>`_
-   * :ref:`using-git`
-   * :ref:`git-resources`
+   * :external+scipy:ref:`using-git`
+   * :external+scipy:ref:`git-resources`
    * `Installing git <https://git-scm.com/book/en/v2/Getting-Started-Installing-Git>`_
    * `Managing remote repositories
      <https://docs.github.com/en/get-started/getting-started-with-git/managing-remote-repositories>`_