[1.7.x] Fixed #23817 -- Updated docs on QuerySet evaluation
[1.7.x] Fixed #23817 -- Updated docs on QuerySet evaluation

Removed inaccurate info about partial evaluation after refs #18702.
Added information on modifying sliced QuerySets; refs #22503.

Backport of 327df551e89a505c5756becee97c40198f38aff2 from master

jyotsna1820/django,jyotsna1820/django,oscaro/django,jyotsna1820/django,oscaro/django,oscaro/django,oscaro/django,jyotsna1820/django