MQTT climate config to integration key (#22826)

source/_integrations/climate.mqtt.markdown

@@ -16,10 +16,32 @@ To enable this climate platform in your installation, first add the following to
 
 ```yaml
 # Example configuration.yaml entry
+mqtt:
+  climate:
+    - name: Study
+      mode_command_topic: "study/ac/mode/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 `climate` 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
 climate:
   - platform: mqtt
+    name: Study
+    mode_command_topic: "study/ac/mode/set"
 ```
 
+{% enddetails %}
+
 {% configuration %}
 action_template:
   description: A template to render the value received on the `action_topic` with.
@@ -380,9 +402,9 @@ Say you receive the operation mode `"auto"` via your `mode_state_topic`, but the
 {% raw %}
 
 ```yaml
-climate:
-  - platform: mqtt
-    name: Study
+mqtt:
+  climate:
+    - name: Study
       modes:
         - "off"
         - "heat"
@@ -404,9 +426,9 @@ A full configuration example looks like the one below.
 
 ```yaml
 # Full example configuration.yaml entry
-climate:
-  - platform: mqtt
-    name: Study
+mqtt:
+  climate:
+    - name: Study
       modes:
         - "off"
         - "cool"