Add SHA-1 Deprecation Warning?

[eduncan911]

So, the default SHA-1 algorithm in openssh will be Deprecated in the near future.

https://www.openssh.com/txt/release-8.2

Millions, billions of people's keys will need to change.

May I suggest adding a Deprecated WARNING when you detect SHA-1 is used and pointing people to the release notes above?

Would be a nice little proactive step to let users know that don't know.

If not, no biggie. Not even the ssh nor sshd give such a warning yet.