Fixed #10218 -- Reworded serialization.txt sentence to remove awkward quotes....

Fixed #10218 -- Reworded serialization.txt sentence to remove awkward quotes. Thanks for bringing this up, thedaniel

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9850 bcc190cf-cafb-0310-a4f2-bffc1f526a37