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

.. class:: TransactionMiddleware

Binds commit and rollback to the request/response phase. If a view function

runs successfully, a commit is done. If it fails with an exception, a rollback

is done.

Binds commit and rollback of the default database to the request/response

phase. If a view function runs successfully, a commit is done. If it fails with

an exception, a rollback is done.

The order of this middleware in the stack is important: middleware modules

running outside of it run with commit-on-save - the default Django behavior.