doc: hwmon: acpi_power_meter: Add information about enabling the power capping feature.

To enable the power capping feature of the acpi_power_meter driver on
systems other than IBM products, you must explicitly specify
the force_cap_on module parameter.

Add information to the documentation about enabling the power capping
feature with this driver, including the above, to improve user convenience.

Signed-off-by: Shinji Nomoto <fj5851bi@fujitsu.com>
Link: https://lore.kernel.org/r/20250520062707.1657667-1-fj5851bi@fujitsu.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>