Move from Wiki to /docs

[akirataguchi115]

GitHub Wiki is an anti-pattern for various reasons: https://michaelheap.com/github-wiki-is-an-antipattern/ . As a developer and as a lecturer the Wiki is hard to navigate. At some point it would be a good idea to move to /docs and maybe host it on Pages: https://docs.github.com/en/communities/documenting-your-project-with-wikis/about-wikis

[nygrenh]

We used the GitHub Wiki because we wanted to use the /docs folder only for developer documentation, and we wanted the user documentation to be in a separate location.

The GitHub Wiki is a convenient solution to archive that goal. However, I do agree that the navigation could be improved.