Something that has been difficult as a developer looking to contribute to this project is trying to understand how everything is organised.
In particular, working out what 'pu' stood for took quite a long time.
Following is a (very) simple patch to the README that will at least send potential contributors off in a useful direction. I know I would have saved much time if this note was there when I started looking.
Potentially, the wiki and public website could be updated to provide similar links and start-up hints.