UDEV rules critical to getting a SCSI scanner working on Ubuntu

Copying my bug against ubuntu-docs here, Bug #440150:

I was researching how to connect a HP 6100C scanner to Ubuntu 9.04, and encountered these docs:

ScanningHowTo
https://help.ubuntu.com/community/ScanningHowTo

Scanning
https://help.ubuntu.com/8.04/printing/C/scanning.html

Neither of these docs stated how to successfully get a scanner which SANE shows is fully supported to actually work.

I discovered this document:

Writing UDEV rules to get a SCSI scanner working on Ubuntu
http://jhansonxi.blogspot.com/2009/08/writing-udev-rules-to-get-scsi-scanner.html

which solved my problems perfectly.

I propose that something about writing UDEV rules needs to be added to the above scanning related documents. Otherwise, SANE reporting a "green check box" for compatibility is USELESS.

Also beyond UDEV rules, make sure that the scanner group has been created and the userid being logged in with is in the scanner group.