svcb: doc updates (#1178)
svcb: doc updates (#1178)

The SVBC record didn't have a class, so add that and use struct literal
to put it all on 1 one. Use `s` for SVCB records, and `h` for HTTPS to
be more consistent.

Signed-off-by: Miek Gieben <00b357f94cf3a1145a32703fb42e2d80418ab806@miek.nl>
miekg/dns