platform/x86: asus-wmi: Document the panel_od sysfs attribute

The panel_od attribute was not documented, this adds the
required documentation.

Fixes: ca91ea34 ("asus-wmi: Add panel overdrive functionality")
Signed-off-by: Luke D. Jones <luke@ljones.dev>
Link: https://lore.kernel.org/r/20220812222509.292692-4-luke@ljones.devReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Documentation/ABI/testing/sysfs-platform-asus-wmi

@@ -77,3 +77,12 @@ Description:
 
 			* 0 - Disable,
 			* 1 - Enable
+
+What:		/sys/devices/platform/<platform>/panel_od
+Date:		Aug 2022
+KernelVersion:	5.17
+Contact:	"Luke Jones" <luke@ljones.dev>
+Description:
+		Enable an LCD response-time boost to reduce or remove ghosting:
+			* 0 - Disable,
+			* 1 - Enable