[isabelle-dev] Isabelle2022 process

[Makarius]

We are already on Isabelle2022-RC1 with Isabelle/6308eaaa88f1, but still on 
the isabelle-dev repository.

This means that ongoing changes are for the release. The fork of the 
isabelle-dev vs. isabelle-release repositories will happen in approx. 1-2 weeks.

Now is still an opportunity to add missing entries to NEWS and CONTRIBUTORS. 
This will eventually also affect ANNOUNCE and thus the website front page.

It would be also great if afp-devel could move faster than usual, and keep 
close to isabelle-release.


	Makarius