Added rails gem on back-end development section

readme.md

@@ -138,6 +138,7 @@ If you want to create your own list, please read the [create list instructions](
 - [Symfony2](https://github.com/EmanueleMinotto/awesome-symfony2)
 - [Laravel](https://github.com/chiraggude/awesome-laravel)
 - [Rails](https://github.com/ekremkaraca/awesome-rails)
+- [Rails Gem](https://github.com/hothero/awesome-rails-gem)
 - [Phalcon](https://github.com/sergeyklay/awesome-phalcon)
 - [Useful `.htaccess` Snippets](https://github.com/phanan/htaccess)
 - [nginx](https://github.com/fcambus/nginx-resources)