ABI: sysfs-class-hwmon: add ABI documentation for it

Move the ABI attributes documentation from:
	Documentation/hwmon/sysfs-interface.rst

in order for it to follow the usual ABI documentation. That
allows script/get_abi.pl to properly handle it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/5f47619ed882b0b8d1c84b56f7ea17bac0854b77.1632994837.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>