Add documentation for unique_id on template platforms (#14052)

Co-authored-by: Franck Nijhof <git@frenck.dev>

source/_integrations/alarm_control_panel.template.markdown

@@ -72,6 +72,10 @@ panels:
           required: false
           type: string
           default: Template Alarm Control Panel
+        unique_id:
+          description: An ID that uniquely identifies this alarm control panel. Set this to an unique value to allow customisation trough the UI.
+          required: false
+          type: string
         value_template:
           description: "Defines a template to set the state of the alarm panel. Only the states `armed_away`, `armed_home`, `armed_night`, `disarmed`, `pending`, `triggered` and `unavailable` are used."
           required: false

source/_integrations/binary_sensor.template.markdown

@@ -51,6 +51,10 @@ sensors:
           description: A list of entity IDs so the sensor only reacts to state changes of these entities. This can be used if the automatic analysis fails to find all relevant entities.
           required: false
           type: [string, list]
+        unique_id:
+          description: An ID that uniquely identifies this binary sensor. Set this to an unique value to allow customisation trough the UI.
+          required: false
+          type: string
         device_class:
           description: Sets the [class of the device](/integrations/binary_sensor/), changing the device state and icon that is displayed on the frontend.
           required: false

source/_integrations/cover.template.markdown

@@ -53,6 +53,10 @@ cover:
         description: A list of entity IDs so the cover only reacts to state changes of these entities. This can be used if the automatic analysis fails to find all relevant entities.
         required: false
         type: [string, list]
+      unique_id:
+        description: An ID that uniquely identifies this cover. Set this to an unique value to allow customisation trough the UI.
+        required: false
+        type: string
       value_template:
         description: Defines a template to get the state of the cover. Valid values are `open`/`true` or `closed`/`false`. [`value_template`](#value_template) and [`position_template`](#position_template) cannot be specified concurrently.
         required: exclusive

source/_integrations/fan.template.markdown

@@ -63,6 +63,10 @@ fan:
         description: Name to use in the frontend.
         required: false
         type: string
+      unique_id:
+        description: An ID that uniquely identifies this fan. Set this to an unique value to allow customisation trough the UI.
+        required: false
+        type: string
       value_template:
         description: "Defines a template to get the state of the fan. Valid value: 'on'/'off'"
         required: true

source/_integrations/light.template.markdown

@@ -74,6 +74,10 @@ light:
         description: A list of entity IDs so the light only reacts to state changes of these entities. This can be used if the automatic analysis fails to find all relevant entities.
         required: false
         type: [string, list]
+      unique_id:
+        description: An ID that uniquely identifies this light. Set this to an unique value to allow customisation trough the UI.
+        required: false
+        type: string
       value_template:
         description: Defines a template to get the state of the light.
         required: false

source/_integrations/lock.template.markdown

@@ -47,6 +47,10 @@ lock:
     required: false
     type: string
     default: Template Lock
+  unique_id:
+    description: An ID that uniquely identifies this lock. Set this to an unique value to allow customisation trough the UI.
+    required: false
+    type: string
   value_template:
     description: Defines a template to set the state of the lock.
     required: true

source/_integrations/switch.template.markdown

@@ -54,6 +54,10 @@ switch:
         description: A list of entity IDs so the switch only reacts to state changes of these entities. This can be used if the automatic analysis fails to find all relevant entities.
         required: false
         type: [string, list]
+      unique_id:
+        description: An ID that uniquely identifies this switch. Set this to an unique value to allow customisation trough the UI.
+        required: false
+        type: string
       value_template:
         description: Defines a template to set the state of the switch. If not defined, the switch will optimistically assume all commands are successful.
         required: false

source/_integrations/template.markdown

@@ -54,6 +54,10 @@ sensor:
         description: A list of entity IDs so the sensor only reacts to state changes of these entities. This can be used if the automatic analysis fails to find all relevant entities.
         required: false
         type: [string, list]
+      unique_id:
+        description: An ID that uniquely identifies this sensor. Set this to an unique value to allow customisation trough the UI.
+        required: false
+        type: string
       unit_of_measurement:
         description: "Defines the units of measurement of the sensor, if any. This will also influence the graphical presentation in the history visualization as a continuous value. Sensors with missing `unit_of_measurement` are showing as discrete values."
         required: false
@@ -104,6 +108,10 @@ If you are using the state of a platform that takes extra time to load, the Temp
 
 The template engine will attempt to work out what entities should trigger an update of the sensor. This can fail, for example, if your template loops over the contents of a group. In this case, you can use `entity_id` to provide a list of entity IDs that will cause the sensor to update or you can run the service `homeassistant.update_entity` to update the sensor at will.
 
+### Unique ID
+
+The optional `unique_id` can be set so the entity will be registered in the [entity registry](https://developers.home-assistant.io/docs/entity_registry_index). This allows changing the `name`, `icon` and `entity_id` from the web interface instead of having to use the [customize](/docs/configuration/customizing-devices/) key in your `configuration.yaml` file.
+
 ## Examples
 
 In this section, you find some real-life examples of how to use this sensor.
@@ -349,7 +357,7 @@ sensor:
 
 Useful entities to choose might be `sensor.date` which update once per day or `sensor.time`, which updates once per minute.  
 Please note that the resulting template will be evaluated by Home Assistant state engine on every state change of these sensors, which in case of `sensor.time` happens every minute and might have a negative impact on performance.
- 
+
 An alternative to this is to create an interval-based automation that calls the service `homeassistant.update_entity` for the entities requiring updates. This modified example updates every 5 minutes:
 
 {% raw %}

source/_integrations/vacuum.template.markdown

@@ -39,6 +39,10 @@ vacuum:
         description: Name to use in the frontend.
         required: false
         type: string
+      unique_id:
+        description: An ID that uniquely identifies this vacuum. Set this to an unique value to allow customisation trough the UI.
+        required: false
+        type: string
       value_template:
         description: "Defines a template to get the state of the vacuum. Valid value: `docked`/`cleaning`/`idle`/`paused`/`returning`/`error`"
         required: false