Add RubyonRails, check_urls=free-programming-books.md (#5136)

free-programming-books.md

@@ -2610,6 +2610,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Building REST APIs with Rails](http://apionrails.icalialabs.com/book)
 * [Kestrels, Quirky Birds, and Hopeless Egocentricity](https://leanpub.com/combinators/read) - Reg Braithwaite
 * [Learn Ruby on Rails as You Modify a Craigslist Clone](http://www.thinkful.com/learn/ruby-on-rails-tutorial/)
+* [Learn Ruby on Rails: Book One](https://leanpub.com/learnrubyonrails) - Daniel Kehoe (PDF, EPUB) *(Leanpub account or valid email requested)*
 * [Objects on Rails](https://web.archive.org/web/20190319201525/http://objectsonrails.com/) - Avdi Grimm
 * [Rails Girls Guides](http://guides.railsgirls.com)
 * [Ruby Notes for Professionals](https://books.goalkicker.com/RubyBook/) - Compiled from StackOverflow Documentation (PDF)