[21u-communication] JDK 21u process changes

[Severin Gehwolf]

On Mon, 2023-12-11 at 11:10 +0100, Severin Gehwolf wrote:
> I'll update this list once this has been set up and jdk21u-dev starts
> collecting changes for 21.0.3.

Update: jdk21u-dev[1] repo has been created and PRs can get created
there. We are still test-driving the workflow in order to see that bugs
get resolved correctly, but this shouldn't stop you from creating PRs
there.

Since jdk21u is the new rampdown repo, please create all your PRs in
the -dev repo for 21u going forward.

Thanks,
Severin

[1] https://github.com/openjdk/jdk21u-dev