hwmon: Update the sysfs interface documentation

* Document the name attribute.
* Document the *_label attributes.
* Drop "typical usage" lists, they no longer match the reality.
* Drop non hardware-monitoring related entries.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>