Update readme with all associated project repositories

[timmwille]

I think there are quite some connected projects here, so we might update the Readme

Fits to the Idea in general to keep it clean @bmen ? But this also should find a good way to integrate the Website or the other way around to link back and forth and short ways to get the bigger picture.

Until the website is finished, this Repo/Readme is the reference linked to from all places and conversations right now.