Add proper README.md

[maxgerhardt]

This project repository lacks a proper representative README.md that would give users much needed insight on what this repo is without vising other websites.

[Florin-Popescu]

Hi!

Partly related, the README in my fork documents some steps on how to extend the project in the future. Would that be good to include in the readme here or in some other file? I would like to delete my fork after everything is upstreamed here, and I think I've gathered some really good information in there that should be saved in here.

[dl8dtl]

I think this would be more suited for an issue tracker or discussion item type.