Converted the Rails style guide and the Ruby style guide to AsciiDoc, too.

Go check it out!
- https://github.com/rubocop-hq/rails-style-guide/
- https://github.com/rubocop-hq/ruby-style-guide/

Why AsciiDoc? It's hard to write a blog post. It's easy to write an email. AsciiDoc was created to be easy to write in the first place.