- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC: r262233

Spelling, grammar and mdoc cleanup.

MFC r258044, r258679, r263990

Adds gpioiic.4 and gpioled.4 man pages. Moves some of the information that
was previously available on gpio.4 to their respectives pages. Add the
cross references on gpioctl.8.

Add gpiobus(4) as a link to gpio(4).

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

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

Correct my inability to do math and provide a GOOD example.

Approved by: re (implicit)

Add gpio(4) man page to attempt to document the current hints based setup of
pin outputs, functions and setup.

Add cross reference in gpioctl(8) for people to find.

This is by no means complete and really only covers gpioled(4) and the
Atheros based systems who expose a few extra hints at boot time.

This should be updated by developers who know more about this system than
I and viewed as the beginning of documentation, not the end.

Reviewed by: adrian
Approved by: re (joel)
MFC after: 2 weeks