Use "./build.sh" to build the manual pages.
You'll need either NodeJS/npm installed (script will then automatically install the npm marked-man package) or /usr/bin/ronn. The latter is a Ruby program packaged on some distributions as rubygem-ronn or ruby-ronn or installable as gem install ronn. The Node marked-man package and ronn from rubygems are two roughly equivalent alternatives for compiling MarkDown into roff/man format.