Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Convert to use a SYNPOSIS section that mentions kernel modules.
Also add "device scbus" where needed.

MFC after: 3 days

Sort sections.

Add a HARDWARE section which lists supported devices. The actual
device listings has been moved (and in some cases more or less
rewritten) from the DESCRIPTION section.

This will be used later for automatically generating device listings
in the Hardware Notes, by parsing the manual pages.

Reviewed in principle by: ru, hrs, trhodes
No objections: -doc, re
Section name inspired by: NetBSD

english(4) police.

mdoc(7) police: overhaul.

Approved by: re

Fix a few typos and nits.

Submitted by: bmah

Add a manual page for the ahd driver.