Small wording improvements to cache.txt

.. versionadded:: 1.0

While Django includes support for a number of cache backends out-of-the-box,

sometimes you will want to use a customised version or your own backend.  To

use an external cache backend with Django, use a Python import path as the

scheme portion (the part before the initial colon) of the ``CACHE_BACKEND``

URI, like so::

sometimes you might want to use a customized cache backend. To use an external

cache backend with Django, use a Python import path as the scheme portion (the

part before the initial colon) of the ``CACHE_BACKEND`` URI, like so::

    CACHE_BACKEND = 'path.to.backend://'

as reference implementations. You'll find the code in the

``django/core/cache/backends/`` directory of the Django source.

Note: Without a really compelling reason, like a host that doesn't support the

them, you should stick to the cache backends included with Django. They've

been really well-tested and are quite easy to use.

Note: Without a really compelling reason, such as a host that doesn't support

the them, you should stick to the cache backends included with Django. They've

been well-tested and are easy to use.

CACHE_BACKEND arguments

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