[HEADSUP] man(1) now uses mandoc

Hi,

The default renderer on HEAD has been switched to mandoc(1) by default
The man(1) command has been instrumented to first test the manpage and fallback
on groff if the man page cannot be rendered with mandoc(1).

If base is built without groff then man(1) recommands to install groff from
packages.

makewhatis(1), apropos(1) have not yet been switched to mandoc(1) equivalent.

Best regards,
Bapt