Contributors guide - PR guide

[mhindman]

• https://github.com/kubernetes/community/tree/master/contributors/guide
• https://github.com/kubernetes/community/blob/master/contributors/guide/pull-requests.md

nothing this crazy but good examples of how the people that want to do a PR can get in and what the ground rules are.. obviously can just be one or two files for this repo not so crazy of a process :)