Fixed misspelling in docs/add_ons.txt from [5432]

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5439 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/add_ons.txt

@@ -7,7 +7,7 @@ with a variety of extra, optional tools that solve common Web-development
 problems.
 
 This code lives in ``django/contrib`` in the Django distribution. This document
-gives a rundown of the packages in ``contrib``, along with any dependancies
+gives a rundown of the packages in ``contrib``, along with any dependencies
 those packages have.
 
 .. admonition:: Note