added social badges on README.md

Author: sumn2u

README.md

@@ -1,5 +1,7 @@
 # Learn JavaScript
 
+[![Pull Requests Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat)](http://makeapullrequest.com)
+[![first-timers-only Friendly](https://img.shields.io/badge/first--timers--only-friendly-blue.svg)](http://www.firsttimersonly.com/)
 [![GitHub issues](https://img.shields.io/github/issues/sumn2u/learn-javascript)](https://github.com/sumn2u/learn-javascript/issues) [![GitHub forks](https://img.shields.io/github/forks/sumn2u/learn-javascript)](https://github.com/sumn2u/learn-javascript/network)
 [![GitHub stars](https://img.shields.io/github/stars/sumn2u/learn-javascript)](https://github.com/sumn2u/learn-javascript/stargazers)
 [![GitHub license](https://img.shields.io/github/license/sumn2u/learn-javascript)](https://github.com/sumn2u/learn-javascript/blob/master/LICENSE)