Fixed a typo in 1.8 release notes.

These release notes cover the `new features`_, as well as some `backwards

incompatible changes`_ you'll want to be aware of when upgrading from Django

1.6 or older versions. We've also `begun the deprecation process for some

1.7 or older versions. We've also `begun the deprecation process for some

features`_, and some features have reached the end of their deprecation process

and `have been removed`_.