Draft of Git Rev News edition 21

Hi,

A draft of a new Git Rev News edition is available here:

  https://github.com/git/git.github.io/blob/master/rev_news/drafts/edition-21.md

Everyone is welcome to contribute in any section either by editing the
above page on GitHub and sending a pull request, or by commenting on
this GitHub issue:

  https://github.com/git/git.github.io/issues/199

You can also reply to this email.

I tried to cc everyone who appears in this edition but maybe I missed
some people, sorry about that.

Thomas, Jakub Narębski (who is now part of the team, welcome Jakub!)
and myself plan to publish this edition on Wednesday November 16.

Thanks,
Christian.