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

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

Fix another broken date

Add a missing word.

Submitted by: gj

Add a manual page for rgephy(4) and reference it as appropriate. The
motivation for having rgephy.4 is to document the special media option
add in r217415.

MFC after: 3 days