[resources] add link to es6 features

Author: hshoff

README.md

@@ -1432,6 +1432,7 @@
   - [Understanding JavaScript Closures](http://javascriptweblog.wordpress.com/2010/10/25/understanding-javascript-closures/) - Angus Croll
   - [Basic JavaScript for the impatient programmer](http://www.2ality.com/2013/06/basic-javascript.html) - Dr. Axel Rauschmayer
   - [You Might Not Need jQuery](http://youmightnotneedjquery.com/) - Zack Bloom & Adam Schwartz
+  - [ES6 Features](https://github.com/lukehoban/es6features) - Luke Hoban
 
 **Books**