Added note to docs/sessions.txt about only being available in development version

    # request.session['foo'] instead of request.session.

    request.session['foo']['bar'] = 'baz'

To change this default behavior, set the ``SESSION_SAVE_EVERY_REQUEST`` setting

to ``True``. If ``SESSION_SAVE_EVERY_REQUEST`` is ``True``, Django will save

the session to the database on every single request.

**Only available in Django development version.** To change this default

behavior, set the ``SESSION_SAVE_EVERY_REQUEST`` setting  to ``True``. If

``SESSION_SAVE_EVERY_REQUEST`` is ``True``, Django will save the session to the

database on every single request.

Note that the session cookie is only sent when a session has been created or

modified. If ``SESSION_SAVE_EVERY_REQUEST`` is ``True``, the session cookie

Default: ``False``

**Only available in Django development version.**

Whether to save the session data on every request. If this is ``False``

(default), then the session data will only be saved if it has been modified --

that is, if any of its dictionary values have been assigned or deleted.