Fixed warnings in admindocs; refs #20126.

* Install the docutils Python module (http://docutils.sf.net/).

* **Optional:** Linking to templates requires the :setting:`ADMIN_FOR`

  setting to be configured.

* **Optional:** Using the admindocs bookmarklets requires the

  :mod:`XViewMiddleware<django.contrib.admindocs.middleware>` to be installed.

* **Optional:** Using the admindocs bookmarklets requires

  ``django.contrib.admindocs.middleware.XViewMiddleware`` to be installed.

Once those steps are complete, you can start browsing the documentation by

going to your admin interface and clicking the "Documentation" link in the

:mod:`Django admin <django.contrib.admin>` as a

:class:`~django.contrib.auth.models.User` with

:attr:`~django.contrib.auth.models.User.is_staff` set to `True`, or that the

:mod:`XViewMiddleware <django.contrib.admindocs.middleware>` is installed and

you are accessing the site from an IP address listed in

:setting:`INTERNAL_IPS`.

``XViewMiddleware`` is installed and you are accessing the site from an IP

address listed in :setting:`INTERNAL_IPS`.