After Unbound 1.23.0, the source of the man pages is in reStructuredText format.

This helps with the online documentation at https://unbound.docs.nlnetlabs.nl
and makes it easier to maintain and contribute to the documentation.

The templated man pages (*.in) are still part of the code repository as to not
alter current procedures that could be in place by users/packagers.

These man pages (*.in) are still the ones being used when
configuring/installing Unbound.
Packagers/users do not have to generate any man pages themselves, this is done
by the core developers during development and upon releasing new versions.

The templated man pages (*.in) are generated by Sphinx (used for the online
documentation).
The online documentation has its own repository at
https://github.com/NLnetLabs/unbound-manual.

In that README.md (https://github.com/NLnetLabs/unbound-manual/README.md)
there are further simple instructions on how to generate the templated man
pages there and update them in this repository.