update light.knx for xknx 0.9.4 (#7979)

* update light.knx for xknx 0.9.3

* remove white_value; add color_temperature_mode

reflect changes from https://github.com/XKNX/xknx/pull/165

* added note for tunable white

added note poiniting out Kelvin/Mireds relationship

* ✏️ Tweaks

source/_components/light.knx.markdown

@@ -13,10 +13,14 @@ ha_release: 0.44
 ha_iot_class: "Local Polling"
 ---
 
+The `knx light` component is used as an interface to control knx actuators for lighting applications such as:
 
-The `knx` light component is used as in interface to switching/light actuators.
+- switching actuators
+- dimming actuators
+- LED controllers
+- DALI gateways
 
-The `knx` component must be configured correctly, see [KNX Component](/components/knx).
+The `knx` component must be configured correctly to use this component, see [KNX Component](/components/knx).
 
 ## {% linkable_title Configuration %}
 
@@ -31,34 +35,107 @@ light:
 
 {% configuration %}
 address:
-  description: KNX group address for switching the light on and off.
+  description: KNX group address for switching the light on and off. *DPT 1.001*
   required: true
   type: string
+state_address:
+  description: KNX group address for retrieving the switch state of the light. *DPT 1.001*
+  required: false
+  type: string
 name:
   description: A name for this device used within Home Assistant.
   required: false
   type: string
 brightness_address:
-  description: KNX group address for dimming light.
+  description: KNX group address for setting the brightness of the light in percent (absolute dimming). *DPT 5.001*
-  required: false
-  type: string
-state_address:
-  description: separate KNX group address for retrieving the switch state of the light.
   required: false
   type: string
 brightness_state_address:
-  description: separate KNX group address for retrieving the dimmed state of the light.
+  description: KNX group address for retrieving the brightness of the light in percent. *DPT 5.001*
   required: false
   type: string
 color_address:
-  description: separate KNX group address for setting the color of the light.
+  description: KNX group address for setting the RGB color of the light. *DPT 232.600*
   required: false
   type: string
 color_state_address:
-  description: separate KNX group address for retrieving the color of the light.
+  description: KNX group address for retrieving the RGB color of the light. *DPT 232.600*
   required: false
   type: string
+color_temperature_address:
+  description: KNX group address for setting the color temperature of the light. *DPT 5.001 or 7.600 based on color_temperature_mode*
+  required: false
+  type: string
+color_temperature_state_address:
+  description: KNX group address for retrieving the color temperature of the light. *DPT 5.001 or 7.600 based on color_temperature_mode*
+  required: false
+  type: string
+color_temperature_mode:
+  description: Color temperature group address data type.
+  keys:
+    absolute: 
+      description: color temperature in Kelvin. *color_temperature_address -> DPT 7.600*
+    relative:
+      description: color temperature in percent cold white (0% warmest; 100% coldest). *color_temperature_address -> DPT 5.001*
+  required: false
+  type: string
+  default: absolute
+min_kelvin:
+  description: Warmest possible color temperature in Kelvin. (Used in combination with *color_temperature_address*)
+  required: false
+  type: integer
+  default: 2700
+max_kelvin:
+  description: Coldest possible color temperature in Kelvin. (Used in combination with *color_temperature_address*)
+  required: false
+  type: integer
+  default: 6000
 {% endconfiguration %}
 
-Some KNX devices can change their state internally without any messages on the KNX bus, e.g., if you configure a timer on a channel. The optional `state_address` can be used to inform Home Assistant about these state changes. If a KNX message is seen on the bus addressed to the given state address, this will overwrite the state of the switch object.
+Many KNX devices can change their state internally without a message to the switch address on the KNX bus, e.g., if you configure a scene or a timer on a channel. The optional `state_address` can be used to inform Home Assistant about these state changes. If a KNX message is seen on the bus addressed to the given `state_address` (in most cases from the light actuator), it will overwrite the state of the switch object.
-For switching/light actuators that are only controlled by a single group address and can't change their state internally, you don't have to configure the state address.
+
+For switching/light actuators that are only controlled by a single group address and don't have dedicated state communication objects you can set `state_address` to the same value as `address`.
+
+*Note on tunable white:* Home-Assistant uses Mireds as the unit for color temperature, whereas KNX typically uses Kelvin. The Kelvin/Mireds relationship is reciprocal, not linear, therefore the color temperature pickers (sliders) in Home-Assistant may not align with ones of KNX visualizations. This is the expected behavior.
+
+## {% linkable_title Extended configuration example %}
+
+```yaml
+light:
+  # dimmable light
+  - platform: knx
+    name: Bedroom-Light-1
+    address: '1/0/9'
+    state_address: '1/1/9'
+    brightness_address: '1/2/9'
+    brightness_state_address: '1/3/9'
+  #
+  # RGB light
+  - platform: knx
+    name: Bathroom-Light-1
+    address: '1/0/9'
+    state_address: '1/1/9'
+    brightness_address: '1/2/9'
+    brightness_state_address: '1/3/9'
+    color_address: '1/4/9'
+    color_state_address: '1/5/9'
+  #
+  # tunable white light
+  - platform: knx
+    name: Office-Light-1
+    address: '1/0/21'
+    state_address: '1/1/21'
+    brightness_address: '1/2/21'
+    brightness_state_address: '1/3/21'
+    color_temperature_address: '1/4/21'
+    color_temperature_state_address: '1/5/21'
+    color_temperature_mode: absolute
+    min_kelvin: 2550
+    max_kelvin: 6200
+  #
+  # actuator without dedicated state communication object
+  - platform: knx
+    name: Cellar-Light-1
+    address: '1/0/5'
+    state_address: '1/0/5'
+```