Improve documentation for device_class (#2073)

source/_components/binary_sensor.markdown

@@ -13,7 +13,7 @@ Binary sensors are gathering information about state of switches, contacts, pins
 
 Knowing that there are only two states allows Home Assistant to represent the sensor better in the frontend.
 
-Most binary sensors support the `device_class:`  which let you specify the type of your sensor. The following types are supported:
+The display style of each entity can be modified in the [customize section](/getting-started/customizing-devices/). The following device classes are supported for binary sensors:
 
 - **None**: Generic on/off
 - **cold**: On means cold (or too cold)

source/_components/cover.markdown

@@ -11,6 +11,12 @@ footer: true
 
 Home Assistant can give you an interface to control covers such as rollershutters, blinds, and garage doors.
 
+The display style of each entity can be modified in the [customize section](/getting-started/customizing-devices/). The following device classes are supported for covers:
+
+- **None**: Generic cover device
+- **window**: Window controller
+- **garage**: Garage door controller
+
 ## {% linkable_title Services %}
 
 ### {% linkable_title Cover control services %}

source/getting-started/customizing-devices.markdown

@@ -48,7 +48,14 @@ homeassistant:
 | `entity_picture` | Url to use as picture for entity
 | `icon` | Any icon from [MaterialDesignIcons.com](http://MaterialDesignIcons.com). Prefix name with `mdi:`, ie `mdi:home`.
 | `assumed_state` | For switches with an assumed state two buttons are shown (turn off, turn on) instead of a switch. By setting `assumed_state` to `false` you will get the default switch icon.
-| `device_class` | Sets the [class of the device](/components/binary_sensor/), changing the device state and icon that is displayed on the UI (see below).
+| `device_class` | Sets the class of the device, changing the device state and icon that is displayed on the UI (see below).
+
+### {% linkable_title Device Class %}
+
+Device class is currently supported by the following platforms:
+
+* [Binary Sensor](/components/binary_sensor/)
+* [Cover](/components/cover/)
 
 ### {% linkable_title Advanced example %}