[docs] add CLI documentation for channel manager/monitor (#6385)
[docs] add CLI documentation for channel manager/monitor (#6385)


openthread/openthread,abtink/openthread,openthread/openthread,abtink/openthread,srickardti/openthread,jwhui/openthread,abtink/openthread,openthread/openthread,jwhui/openthread,jwhui/openthread,srickardti/openthread,openthread/openthread,jwhui/openthread,srickardti/openthread,srickardti/openthread,abtink/openthread