Fixed a couple of typos in docs/contributing.txt
Fixed a couple of typos in docs/contributing.txt

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4347 bcc190cf-cafb-0310-a4f2-bffc1f526a37

--HG--
extra : convert_revision : 91c9b57d1c4087e914d641a8f4ff72d46d323bef

adieu/django-nonrel,adieu/django-nonrel,heracek/django-nonrel,adieu/django-nonrel,heracek/django-nonrel,heracek/django-nonrel