Update django-mongodb-backend usage docs

Author: aclark4life

docs/source/usage/django-mongodb-backend.rst

@@ -2,7 +2,12 @@ Run django-mongodb-backend tests
 --------------------------------
 
 The :ref:`Django fork <mongodb-django-fork>` test runner also runs
-the django-mongodb-backend tests. You can list them with the
+the django-mongodb-backend tests.
+
+List tests
+~~~~~~~~~~
+
+You can list them with the
 ``dm repo test django -l`` command.
 
 ::
@@ -11,6 +16,10 @@ the django-mongodb-backend tests. You can list them with the
 
 .. image:: ../_static/images/django-mongodb-backend.png
 
+
+Run tests
+~~~~~~~~~
+
 Then you can run them by specifying the test module e.g. to run
 the tests for the ``backend`` module::