ABI: testing: sysfs-class-power: clarify charge_type documentation

The existing docs here are a bit vague. This reformats and rewords it,
and is based upon the wording originally used by the dell-laptop driver
battery documentation and also sysfs-class-power-wilco.

The wording for "Long Life" and "Bypass" remain the same, because I'm
unfamiliar with hardware that use them.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240820041942.30ed42f3@5400


Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>