Create CONTRIBUTING.md

GitHub suggests putting a CONTRIBUTING.md in the repository. https://github.com/blog/1184-contributing-guidelines

Currently, we have such content at Confluence. We can either just link people to Confluence, move those confluence pages to this file, or forget about making this file in the repo.
Just curious. Is there a way to alias "@devteam" and "@owners" (maybe as "devcore" ?) to simplify? It isn't strictly necessary, since we already get notified, but it makes the following the policy easier. You can just ask @devteam or @devcore  to review.

In hindsight this isn't that helpful either. Perhaps it is more important to say that the PR will be evaluated by 2 devteam members, etc... then state that it is a requirement. Since most don't have write privileges and they cannot choose who reviews their PR, it is completely up to the devteam to enact the policy. In which case, it would make sense to have a separate PR review and merge requirements doc with these policies for devteam members to follow.