Fixed some typos

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In Django 1.1, the template tag did not exist.  Instead, a post-processing

middleware that re-wrote POST forms to include the CRSF token was used.  If you

middleware that re-wrote POST forms to include the CSRF token was used.  If you

are upgrading a site from version 1.1 or earlier, please read this section and

the `Upgrading notes`_ below.  The post-processing middleware is still available

as ``CsrfResponseMiddleware``, and it can be used by following these steps:

Use of the ``CsrfResponseMiddleware`` is not recommended because of the

performance hit it imposes, and because of a potential security problem (see

below).  It can be used as an interim measure until applications have been

updated to use the ``{% crsf_token %}`` tag.  It is deprecated and will be

updated to use the ``{% csrf_token %}`` tag.  It is deprecated and will be

removed in Django 1.4.

Django 1.1 and earlier provided a single ``CsrfMiddleware`` class.  This is also