[TLS] ECH status

ECH has been revised based on working group input and is ready to go to the IESG. You can see the diff between the latest (-22) and the one published previous to the last IETF (-18) here: https://author-tools.ietf.org/iddiff?url1=draft-ietf-tls-esni-18&url2=draft-ietf-tls-esni-22&difftype=--html .

[TLS] ECH Status

I've finished my shepherd review and there are 3 PRs to merge (#625 , #624 , #623 ) There is also one additional editorial PR (#622