Removes Free React on Rails course (#5337)

Unfortunately not free but 50$ online course :/

books/free-programming-books.md

@@ -1914,7 +1914,6 @@ Kerridge (PDF) (email address *requested*, not required)
 
 #### React
 
-* [Free React on Rails course](https://learnetto.com/users/hrishio/courses/the-free-react-on-rails-5-course)
 * [Full-Stack React Projects](https://www.packtpub.com/free-ebooks/full-stack-react-projects) - Shama Hoque (Packt account *required*)
 * [Hacking with React](http://www.hackingwithreact.com)
 * [Intro to the React Framework](http://code.tutsplus.com/tutorials/intro-to-the-react-framework--net-35660)