Delete the GitHub Wiki

[Lawrence Chonavel]

The GitHub wiki for this repo currently contains only stubs,
and has not been touched since Oct 2023.

It should be deleted to:

• Avoid fragmentation (we already have the issue tracker, notes in the repo, code comments, user docs, etc.)
• Streamline devx (fewer tabs in GitHub)

[Jesper Cockx]

Agreed, I had already forgotten we had activated it.

[Andreas Abel]

We can use it to have random materials not related to specific issues, like I put a dev meeting protocol there in Oct 2023.
Maybe we should put our meeting protocols there more consistently. (I confess I forgot about it.)

[Lawrence Chonavel]

We already have several other stores of "random materials":

• The notes/ directory of this repo
• The Chalmers Wiki (see also #7126)
• Issue tracker comments
  • e.g. one of the meeting notes is at #3758 (comment)