nixos/sane: mention sane-airscan in the extraBackends option

It's a very useful backend (that probably should be enabled by default,
like on Ubuntu), let's start by making it easier to discover.

Ref https://github.com/NixOS/nixpkgs/issues/28406.

Changed files
+4 -2
nixos
modules
services
hardware
+4 -2
nixos/modules/services/hardware/sane.nix
···
Packages providing extra SANE backends to enable.
::: {.note}
-
The example contains the package for HP scanners.
+
The example contains the package for HP scanners, and the package for
+
Apple AirScan and Microsoft WSD support (supports many
+
vendors/devices).
:::
'';
-
example = literalExpression "[ pkgs.hplipWithPlugin ]";
+
example = literalExpression "[ pkgs.hplipWithPlugin pkgs.sane-airscan ]";
};
hardware.sane.disabledDefaultBackends = mkOption {