Documentation/ABI: Add new attributes for mlxreg-io sysfs interfaces

Add documentation for the new attributes:
- "asic2_health" - health of 2-nd ASIC for system equipped with two ASICs.
- "asic_reset" and "asic2_reset" - ASICs reset control.
- "comm_chnl_ready" - communication channel indication to remote end (BMC).
- "config3" - indication of system minor BOM changes.

Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220711084559.62447-10-vadimp@nvidia.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>