This matches what has been recommended in the FDP primer, and is the
style I recommened in my talk at BSDCan '25. I have deliberately made
this minimal to preserve nuance and avoid bloating the doc, since we
already have a lot of trouble getting people to read all the different
style guides on commit messages, the language itself, the style in the
fdp primer, and the freebsd manpages style manual.
MFC after: 3 days