SHA2 certificates

[nicdumz]

(Following up on #1144)

SHA1 certificates are being faded out, it could be useful to figure out / confirm that SHA2 is a reasonable alternative.
According to https://www.digicert.com/sha-2-compatibility.htm , support shouldn't be problematic anymore.

A redirect/glossary entry seems reasonable

[JaneX8]

+1

[JaneX8]

Also apart from a SHA2 compatibility list it would be nice to see the inverse list of SHA1 till what versions is was supported and in which browsers support is currently dropped.

[nicdumz]

My understanding is that browser which support https://caniuse.com/tls1-2 can implicitly support SHA2 certificates, so perhaps redirecting to that entry is good enough