Describes the layout of this repo. This should help contributors navigate and and find what they're looking for much faster than just stumbling around.
I have experience with both contributing to and maintaining open-source projects. One of the lessons I’ve learned is that the biggest difference between an occasional contributor and a core developer lies in the knowledge about the physical architecture of the project. Roughly, it takes 2x more time to write a patch if you are unfamiliar with the project, but it takes 10x more time to figure out where you should change the code.
Also add a README and remove the outdated HACKING.