On: Ruby hacking guide

[djacobs]

I'm happy to contribute, too -- let me know if you're interested in any help with editing or creating/maintaining a PDF.

[markburns → djacobs]

Absolutely :) https://github.com/ruby-hacking-guide/ruby-hacking-guide.git... I'm taking the approach of trusting first, so if your first PR isn't insane, then no reason not to add you to the team.