Project documentation with Markdown.

Background: https://groups.google.com/forum/#!topic/django-rest-framework/YJ6J3jocGlo

See in progress docs: www.mkdocs.org

Release notes: http:https://www.mkdocs.org/about/release-notes/

Project roadmap: https://github.com/tomchristie/mkdocs/wiki

IRC channel: #mkdocs on freenode.