Add note about Onkyo WAVIO.
 [sape] --rw-rw-r-- M 82708 glenda sys 4546 Sep 20 04:24 sys/man/4/usb
	/n/sourcesdump/2005/0920/plan9/sys/man/4/usb:197,199 - 
	/n/sourcesdump/2005/0921/plan9/sys/man/4/usb:197,203
	  Xitel Pro HiFi-Link
	  Playback only.  48 KHz only.  There is a volume control but it isn't connected
	  to the output, so does nothing.
	+ .TP
	+ Onkyo WAVIO series MA-500U
	+ Includes three optical digital interfaces, two analog, and an
	+ amplifier (15W + 15W).