[1.5.X] Fixed typo in docs/ref/models/querysets.txt
[1.5.X] Fixed typo in docs/ref/models/querysets.txt

Backport of 76859e6eab from master

imtapps/django-imt-fork,ccn-2m/django,alx-eu/django,hasadna/django,alx-eu/django,ccn-2m/django,bliti/django-nonrel-1.5,hasadna/django,ccn-2m/django,imtapps/django-imt-fork,ccn-2m/django,hasadna/django,alx-eu/django,alx-eu/django,bliti/django-nonrel-1.5,imtapps/django-imt-fork,bliti/django-nonrel-1.5