Prototype Nix-based roadmap on roadmap.sh

[sshine]

The https://roadmap.sh platform is partially closed source, so it cannot be forked and remade with a strict Nix focus. Its interactive diagram rendering is the magic sauce, and we can simply try out the idea of making Nix roadmaps on this platform to the benefit of the platform's users, until an investment is made in similar technology off of that site.