Fixed FR locale for mozilla developer page (mbeaudru#40)

Also add SO link

readme.md

@@ -19,12 +19,13 @@ Besides, I will sometimes provide personal tips that may be debatable but will t
 
 When you struggle to understand a notion, I suggest you look for answers on the following resources:
 
-- [MDN (Mozilla Developer Network)](https://developer.mozilla.org/fr/search?q=)
+- [MDN (Mozilla Developer Network)](https://developer.mozilla.org/en-US/search?q=)
 - [You don't know JS (book)](https://github.com/getify/You-Dont-Know-JS)
 - [ES6 Features with examples](http://es6-features.org)
 - [WesBos blog (ES6)](http://wesbos.com/category/es6/)
 - [Reddit (JavaScript)](https://www.reddit.com/r/javascript/)
 - [Google](https://www.google.com/) to find specific blog and resources
+- [StackOverflow](https://stackoverflow.com/questions/tagged/javascript)
 
 ## Table of Contents