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)

Add reference to led(4), supported now.
Add some details about supported chips.

Change licenses of my manual pages to the recommended 2-clause form.

Suggested by: joel

Add links to cam(4).

Some style and language improvements.

Submitted by: ru

Add `siis` CAM driver for SiliconImage SiI3124/3132/3531 SATA2 controllers.

Driver supports Serial ATA and ATAPI devices, Port Multipliers
(including FIS-based switching), hardware command queues (31 command
per port) and Native Command Queuing. This is probably the second on
popularity, after AHCI, type of SATA2 controllers, that benefits from
using CAM, because of hardware command queuing support.

Approved by: re (kib)