Mailing list migration

[Kensei Nakada]

Hi team,

I'm now working on the mailing list migration.

https://github.com/kubernetes/community/issues/8437

Previously, we had used kubernetes-s...@googlegroups.com, but a new mailing list would be sig-sch...@kubernetes.io.

We just copied the members from the old one to the new one. So, you should be joining the new one now.

I just locked the old mailing list so that a new member wouldn't join mistakenly.

I will start updating the references to the old mailing list. 

Subproject maintainers, please help check your projects (like RELEASE.md), and update the email address there as necessary. The announcements for releases etc should be sent to a new one.

If you have any questions or concerns, please let me know.

Best,

Kensei Nakada (@sanposhiho)