Update alarm_control_panel.mqtt.markdown with unique_id and device (#7863)

* Update alarm_control_panel.mqtt.markdown

* Update alarm_control_panel.mqtt.markdown

source/_components/alarm_control_panel.mqtt.markdown

@@ -43,6 +43,10 @@ name:
   required: false
   type: string
   default: MQTT Alarm
+unique_id:
+   description: An ID that uniquely identifies this alarm panel. If two alarm panels have the same unique ID, Home Assistant will raise an exception.
+   required: false
+   type: string
 state_topic:
   description: The MQTT topic subscribed to receive state updates.
   required: true
@@ -89,4 +93,33 @@ payload_not_available:
   required: false
   type: string
   default: offline
+device:
+  description: 'Information about the device this alarm panel is a part of to tie it into the [device registry](https://developers.home-assistant.io/docs/en/device_registry_index.html). Only works through [MQTT discovery](/docs/mqtt/discovery/) and when [`unique_id`](#unique_id) is set.'
+  required: false
+  type: map
+  keys:
+    identifiers:
+      description: 'A list of IDs that uniquely identify the device. For example a serial number.'
+      required: false
+      type: list, string
+    connections:
+      description: 'A list of connections of the device to the outside world as a list of tuples `[connection_type, connection_identifier]`. For example the MAC address of a network interface: `"connections": [["mac", "02:5b:26:a8:dc:12"]]`.'
+      required: false
+      type: list
+    manufacturer:
+      description: 'The manufacturer of the device.'
+      required: false
+      type: string
+    model:
+      description: 'The model of the device.'
+      required: false
+      type: string
+    name:
+      description: 'The name of the device.'
+      required: false
+      type: string
+    sw_version:
+      description: 'The firmware version of the device.'
+      required: false
+      type: string
 {% endconfiguration %}