MQTT scene config to integration key (#22832)

source/_integrations/scene.mqtt.markdown

@@ -16,11 +16,30 @@ To enable a MQTT scene in your installation, add the following to your `configur
 
 ```yaml
 # Example configuration.yaml entry
+mqtt:
+  scene:
+    - command_topic: zigbee2mqtt/living_room_group/set
+```
+
+<a id='new_format'></a>
+
+{% details "Previous configuration format" %}
+
+The configuration format of manual configured MQTT items has changed.
+The old format that places configurations under the `scene` platform key
+should no longer be used and is deprecated.
+
+The above example shows the new and modern way,
+this is the previous/old example:
+
+```yaml
 scene:
   - platform: mqtt
     command_topic: zigbee2mqtt/living_room_group/set
 ```
 
+{% enddetails %}
+
 {% configuration %}
 availability:
   description: A list of MQTT topics subscribed to receive availability (online/offline) updates. Must not be used together with `availability_topic`.
@@ -132,16 +151,16 @@ The example below shows a full configuration for a scene.
 
 ```yaml
 # Example configuration.yaml entry
-scene:
-  - platform: mqtt
-    unique_id: living_room_party_scene
-    name: "Living Room Party Scene"
-    command_topic: "home/living_room/party_scene/set"
-    availability:
-      - topic: "home/living_room/party_scene/available"
-    payload_on: "ON"
-    qos: 0
-    retain: true
+mqtt:
+  scene:
+    - unique_id: living_room_party_scene
+      name: "Living Room Party Scene"
+      command_topic: "home/living_room/party_scene/set"
+      availability:
+        - topic: "home/living_room/party_scene/available"
+      payload_on: "ON"
+      qos: 0
+      retain: true
 ```
 
 ### Use with a JSON Payload
@@ -150,10 +169,10 @@ The example below shows a configuration using a JSON payload.
 
 ```yaml
 # Example configuration.yaml entry
-scene:
-  - platform: mqtt
-    name: Living Room Blue Scene
-    unique_id: living_room_blue_scene
-    command_topic: "home/living_room/set"
-    payload_on: '{"activate_scene": "Blue Scene"}'
+mqtt:
+  scene:
+    - name: Living Room Blue Scene
+      unique_id: living_room_blue_scene
+      command_topic: "home/living_room/set"
+      payload_on: '{"activate_scene": "Blue Scene"}'
 ```