[1.5.x] Minor edits to docs/topics/db/queries.txt.
[1.5.x] Minor edits to docs/topics/db/queries.txt.

Backport of 8bfc7cc64c from master

ccn-2m/django,ccn-2m/django,ccn-2m/django,bliti/django-nonrel-1.5,ccn-2m/django,bliti/django-nonrel-1.5,bliti/django-nonrel-1.5