hwmon: (w83627hf) Document W83627THF voltage pin mapping

I had to look it up for one user, so we might as well store it in the
driver documentation.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>

diff --cc Documentation/hwmon/w83627hf
Simple merge