Changes Coq into Rocq

[thery]

Update the meta.yml

[thery]

@palmskog This was meant to be a quick PR to see if I can merge.
Still before merging there are some issues:

• I had to remove the coqdoc stuff (the latest doc was for 8.15). Is there something similar in Rocq.
• The generate has changed the build from dune to make. Has the default changed?

[palmskog]

@thery I usually let the opam files use Dune to test both make and Dune builds in CI. But fine by me to switch to testing make builds only.

The coqdoc thing is a more general problem, it has to be solved at infrastructure level, I guess we just remove coqdoc everywhere for now...