Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

A number of places in the source tree still reference cuad.* after
sio(4) was deprecated by uart(4).

s/cuad/cuau/g/

PR: docs/171533
Reviewed by: imp
Approved by: cperciva (implicit)
MFC after: 3 weeks

Fix markup (in the same way as it was fixed in tip.1) and thus
make the diffs against tip.1 minimal (as in OpenBSD).

This commit was generated by cvs2svn to compensate for changes in r161751,
which included commits to RCS files with non-trunk default branches.

Import OpenBSD's tip(1) as of today