hwmon: (asus-ec-sensors) update documentation

Signed-off-by: Eugene Shalygin <eugene.shalygin@gmail.com>
Link: https://lore.kernel.org/r/20220124015658.687309-3-eugene.shalygin@gmail.com


Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Denis Pauk <pauk.denis@gmail.com>
[groeck: update index.rst, do not drop asus_wmi_ec_sensors.rst]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>