Delete duplicate Django entry for Tango With Django

free-programming-books.md

@@ -1329,7 +1329,6 @@ See also [TeX](#tex)
 * [Django by Example](http://www.lightbird.net/dbe/)
 * [Django by Example for Django 1.5](http://lightbird.net/dbe2/)
 * [Effective Django](http://effectivedjango.com/)
-* [Tango With Django](http://www.tangowithdjango.com/book/)
 * [Deploy Django](http://www.deploydjango.com)
 * [The Django Book](http://www.djangobook.com)
 * [Tango With Django](http://www.tangowithdjango.com/)