added link to Directory of free Javascript ebooks (#2630)

*  added link to Directory of free Javascript ebooks

* link fix Directory of free Javascript ebooks and sorting in alphabetical order

* updated link

*  Sorry, Corrigir e retirei o link

* Revert "correcting and removing the link

This reverts commit 5059e43931299d7fcdd017ae53c8c742ea36dd1f.

free-programming-books.md

@@ -1394,6 +1394,7 @@
 * [Crockford's JavaScript](http://www.crockford.com/javascript/) - Douglas Crockford
 * [Dev Docs](http://devdocs.io)
 * [Developing Backbone.js Applications](http://addyosmani.github.io/backbone-fundamentals/) - Addy Osmani
+* [Directory of free Javascript ebooks](http://jsbooks.revolunet.com)
 * [Eloquent JavaScript 2nd edition](http://eloquentjavascript.net) - Marijn Haverbeke
 * [Exploring ES6](http://exploringjs.com/es6/) - Dr. Axel Rauschmayer
 * [Google JavaScript Style Guide](https://google.github.io/styleguide/javascriptguide.xml)