https://datatracker.ietf.org/doc/html/draft-ietf-dnsop-nsec3-guidance-10
is on it's way to become RFC, so let's update our recommendations in the
docs to be in line with it.
The default values for dnssec-policy and dnssec-signzone were adapted to
match v9_16 branch.
(cherry picked from commit 2ee3f4e6c8)