Added missing request argument to example in URL dispatcher docs

    )

In this example, for a request to ``/blog/2005/``, Django will call

``blog.views.year_archive(year='2005', foo='bar')``.

``blog.views.year_archive(request, year='2005', foo='bar')``.

This technique is used in the

:doc:`syndication framework </ref/contrib/syndication>` to pass metadata and