Adding "A pragmatic guide to Backbone.js apps"

free-programming-books.md

@@ -689,6 +689,7 @@
 * [Developing Backbone.js Applications](http://addyosmani.github.io/backbone-fundamentals/)
 * [A Complete guide for learning Backbone.js](http://www.codebeerstartups.com/2012/12/a-complete-guide-for-learning-backbone-js/)
 * [Backbonejs Tutorials](http://backbonetutorials.com/)
+* [A pragmatic guide to Backbone.js apps](http://pragmatic-backbone.com/)
 
 ####D3.js