sane service: mention the lp group for printer+scanners

Changed files
+1 -1
nixos
modules
services
hardware
+1 -1
nixos/modules/services/hardware/sane.nix
···
Enable support for SANE scanners.
<note><para>
-
Users in the "scanner" group will gain access to the scanner.
+
Users in the "scanner" group will gain access to the scanner, or the "lp" group if it's also a printer.
</para></note>
'';
};