Minor fixes in the custom template tags docs.

If you leave off the ``name`` argument, as in the second example above, Django

will use the function's name as the filter name.

Finally, ``register.filter()`` also accepts two keyword arguments, ``is_safe``

and ``needs_autoescape``, described in :ref:`filters and auto-escaping

<filters-auto-escaping>` below.

Finally, ``register.filter()`` also accepts three keyword arguments,

``is_safe``, ``needs_autoescape``, and ``expects_localtime``. These arguments

are described in :ref:`filters and auto-escaping <filters-auto-escaping>` and

:ref:`filters and time zones <filters-timezones>` below.

Template filters that expect strings

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When this flag is set, if the first argument to your filter is a time zone

aware datetime, Django will convert it to the current time zone before passing

to your filter when appropriate, according to :ref:`rules for time zones

it to your filter when appropriate, according to :ref:`rules for time zones

conversions in templates <time-zones-in-templates>`.

Writing custom template tags