Changed note about update_fields and pre_save() to admonition.
Follow up to
@@ -621,7 +621,7 @@ from the DB will get updated. In effect there is an automatic
``update_fields`` in this case. If you assign or change any deferred field
value, the field will be added to the updated fields.
-.. note::
+.. admonition:: ``Field.pre_save()`` and ``update_fields``
If ``update_fields`` is passed in, only the
:meth:`~django.db.models.Field.pre_save` methods of the ``update_fields``
