Added a note about the default timezone and the new project template.

A string representing the time zone for this installation, or ``None``. See

the `list of time zones`_.

.. note::

    Since Django was first released with the :setting:`TIME_ZONE` set to

    ``'America/Chicago'``, the global setting (used if nothing is defined in

    your project's ``settings.py``) remains ``'America/Chicago'`` for backwards

    compatibility. New project templates default to ``'UTC'``.

Note that this isn't necessarily the time zone of the server. For example, one

server may serve multiple Django-powered sites, each with a separate time zone

setting.