Reword upgrade note about removal of Page/Site from Django admin

docs/releases/2.8.rst

@@ -126,7 +126,7 @@ The ``get_document_model`` function should now be imported from ``wagtail.docume
 Removed ``Page`` and ``Site`` models from Django admin 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Django admin will no longer provide editing access to ``Page`` or ``Site`` models, if required these models can be registered within individual projects using `Django's ModelAdmin <https://docs.djangoproject.com/en/2.2/ref/contrib/admin/#modeladmin-objects>`_.
+The ``Page`` and ``Site`` models are no longer editable through the Django admin backend. If required these models can be re-registered within your own project using `Django's ModelAdmin <https://docs.djangoproject.com/en/2.2/ref/contrib/admin/#modeladmin-objects>`_:
 
 
 .. code-block:: python