[1.6.x] Corrected a usage example of `related_query_name`.
[1.6.x] Corrected a usage example of `related_query_name`.

Thanks to Petr Glotov for spotting this.

Backport of 05a8cef428 from master

felixjimenez/django,redhat-openstack/django,django-nonrel/django,felixjimenez/django,redhat-openstack/django,felixjimenez/django,redhat-openstack/django,django-nonrel/django,redhat-openstack/django,django-nonrel/django,django-nonrel/django,felixjimenez/django