Document that Ethernet works for the Canon MB5300 Series

See https://alioth-lists.debian.net/pipermail/sane-devel/2018-September/036346.html

doc/descriptions/pixma.desc

@@ -1200,7 +1200,7 @@
 :comment "Flatbed works, All resolutions supported (up to 1200DPI), ADF does not work"
 
 :model "MAXIFY MB5300 Series"
-:interface "USB"
+:interface "USB Ethernet"
 :usbid "0x04a9" "0x1777"
 :status :good
 :comment "1200dpi scans do not work"