troff man page builds have been deprecated as part of Machinekit

The first port of call for manual pages (and all documentation) should be the website.

www.machinekit.io

From the right hand side bar - which is visible from anywhere in the 'Documentation' section, select either

http://www.machinekit.io/docs/man/man1/  For information on utilities and GUIs
http://www.machinekit.io/docs/man/man3/  For information on the hal and rtapi APIs
http://www.machinekit.io/docs/man/man9/  For information on components and drivers

To cater for terminal viewing locally, a second option is available

A Package called 'machinekit-manual-pages' is now automatically created as part of the website build process.

This is available from deb.machinekit.io as per any other package.
The manual pages will then be available at /usr/share/doc/machinekit/man

You can display the pages easily with the asciidoctor plugin for firefox
https://addons.mozilla.org/en-GB/firefox/addon/asciidoctorjs-live-preview/
or for chrome
https://chrome.google.com/webstore/detail/asciidoctorjs-live-previe/iaalpfgpbocpdfblpnhhgllgbdbchmia?hl=en

Alternately, for a terminal display of manual pages, Machinekit now contains a script called mank.
Invoking 'mank debounce' for instance, will display the manual page for the component debounce

mank uses asciidoctor and elinks and will prompt for their installation if not present.
They were not made dependencies of the machinekit package deliberately, as the overwhelming majority of users are likely
to simply use the web site and never install the local manual pages.

(NB If you are a developer and use the --view-doc option to (inst)comp, you will need asciidoctor and elinks for that to operate.)