[13u notice] transition to Git, GitHub, and Skara

[Yuri Nesterenko]

Hi all,

as you know, the final transition of current jdk (JDK 16) to Git, GitHub, and Skara
will be early in September [1]. At that moment, jdk/jdk repository hosted in GitHub will become
read/write master for JDK 16.

Now, JDK 13u seems a natural candidate to try the similar transition
of an update repository. We plan to do it for 13.0.6 release.
So we'll close JDK 13u-dev Mercurial team repo for the current 13.0.5 release
approximately on September 20 (according to schedule) and soon re-open it for the next release
already in Git. The master repository JDK 13u will be transformed after the October release
approximately in early November.

That means the Mercurial repositories [2] and [3] will become read-only, and
new change requests for 13u will start as GitHub pullback requests.

Note that there already are read-only GitHub mirrors of JDK 13u repositories [4], [5].
The actual URLs, exact dates etc. will be announced later ASAP.

Thank you!
--yan

[1] https://mail.openjdk.java.net/pipermail/jdk-dev/2020-May/004322.html
[2] http://hg.openjdk.java.net/jdk-updates/jdk13u-dev/
[3] http://hg.openjdk.java.net/jdk-updates/jdk13u/
[4] https://github.com/openjdk/jdk13u-dev
[5] https://github.com/openjdk/jdk13u