Added a course in Web Development (#2618)

* Added a course in Web Development

Added Freecodecamp in web development. Free code camp is a free course featuring building projects and getting certificates.

* update free code camp in alphabetical order

free-courses-en.md

@@ -356,5 +356,6 @@
 
 * [Discover Flask - Full Stack Web Development with Flask](https://github.com/realpython/discover-flask)
 * [Flask(A Python Microframework) Tutorial](http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-hello-world)
+* [Free Code Camp](https://www.freecodecamp.org)
 * [The Odin Project - Learn Web Development for Free](http://www.theodinproject.com)
 * [Udacity Web Development Course Catalog](https://www.udacity.com/courses#!/web-development#!/web-development)