> you could petition the unbound project to convert their pages to mdoc
> format. better still, convert them yourself and submit those.
No, please don't.
Last time we talked to upstream (NLnet Labs) about this topic (in the
summer of 2014), they explicitly said they wanted to keep using man(7),
admittedly only citing weak reasons ("we don't need semantic markup
for these pages", which implies that they don't care about hyperlinks).
The rejection may also be motivated by using man(7) conistently for
all their projects including nsd(8), ldns, OpenDNSSEC, Net::DNS(3p),
and so on (though that's merely my guess).
So this is neither a technical question nor merely a question of doing
the work to modernize. It is a political question, and solving it
requires diplomacy and system integration / build system design skills.