The man pages don't change very often, but draw in both docbook and
asciidoc. The latter is particularly problematic, as some distros
still ship only a python2 version of the tool.
Address this by generating the man pages at dist time, and including
the result in the tarball.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1553>
