This may be confiusing, for example one may think that
`qvm-prefs --unset vmname netvm` will make vmname network-disconnected.
This type of mistakes may have severe security consequence, so better
drop those option names.
QubesOS/qubes-issues#3002
cc @rootkovska
Most of them are moved from core-admin repository, even if tool is not
implemented yet. Some are generated using skel-manpage.py script.
This way we have complete man pages list, and sphinx will properly
warn/error about inconsistencies.
