doc: Introduce the Adv Monitor Device Found/Lost events

doc: Introduce the Adv Monitor Device Found/Lost events

This patch introduces two new MGMT events
MGMT_EV_ADV_MONITOR_DEVICE_FOUND and MGMT_EV_ADV_MONITOR_DEVICE_LOST to
indicate that the controller has started/stopped tracking a particular
device matching one of the already added Advertisement Monitor.

If the controller offloading support is not available,
MGMT_EV_ADV_MONITOR_DEVICE_FOUND event is also used to report all
advertisements to perform software based filtering whenever we are not
active scanning.

Reviewed-by: Miao-chen Chou <mcchou@google.com>
Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>