Fixed #11022: documented that the admin bulk delete action calls...

.. image:: _images/user_actions.png

.. warning::

    The "delete selected objects" action uses :meth:`QuerySet.delete()

    <django.db.models.QuerySet.delete>` for efficiency reasons, which has an

    important caveat: your model's ``delete()`` method will not be called.

    If you wish to override this behavior, simply write a custom action which

    accomplishes deletion in your preferred manner -- for example, by calling

    ``Model.delete()`` for each of the selected items.

    For more background on bulk deletion, see the documentation on :ref:`object

    deletion <topics-db-queries-delete>`.

Read on to find out how to add your own actions to this list.

Writing actions