ABI: sysfs-class-hwmon: add a description for fanY_fault

Document existing fanY_fault attribute.
Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
Link: https://lore.kernel.org/r/20221130200846.4226-3-nick.hawkins@hpe.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/ABI/testing/sysfs-class-hwmon

@@ -276,6 +276,15 @@ Description:
 
 		RW
 
+What:		/sys/class/hwmon/hwmonX/fanY_fault
+Description:
+		Reports if a fan has reported failure.
+
+		- 1: Failed
+		- 0: Ok
+
+		RO
+
 What:		/sys/class/hwmon/hwmonX/pwmY
 Description:
 		Pulse width modulation fan control.