Building the man page is optional and happens automatically if command
'lowdown' is present on the system. Add it to all possible GitHub CI files
so man page conversion will be tested and fully used.
Unfortunately 'lowdown' cannot be added to the musl jobs the program is
available only starting from Alpine v3.15, while the musl Docker images
run Alpine v3.14 (and haven't been updated in 2+ years).
Also, the Snap build used Ubuntu 20.04 "Focal" which equally is too old
to include Lowdown, which is available only from Ubuntu 22.04 "Jammy"
onward:
https://packages.ubuntu.com/search?suite=all&searchon=names&keywords=lowdown
