[1.7.x] Added translation.override() context manager to docs.
[1.7.x] Added translation.override() context manager to docs.

Backport of cf34ee68f0d70cfbcba40524b5d1086ad94874e1 from master

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