[1.6.x] Reference Meta.index_together in DB performance guide.
[1.6.x] Reference Meta.index_together in DB performance guide.

9dc45efeba from master.

felixjimenez/django,felixjimenez/django,django-nonrel/django,felixjimenez/django,django-nonrel/django,django-nonrel/django,redhat-openstack/django,dex4er/django,dex4er/django,redhat-openstack/django,dex4er/django,django-nonrel/django,felixjimenez/django,redhat-openstack/django,redhat-openstack/django