[1.4.X] Fixed #14165 - Documented that TransactionMiddleware only applies to the default database.
[1.4.X] Fixed #14165 - Documented that TransactionMiddleware only applies to the default database.

Backport of 938ee7cd36 from master

riklaunim/django-custom-multisite,riklaunim/django-custom-multisite,riklaunim/django-custom-multisite