Added doc for homekit (#4720)

* Added doc for homekit

* Fixed typos

* Fixed typos 2

* Removed iot_class

* Add logo, some cleanup

* Update homekit.markdown

* Changed types to components

source/_components/homekit.markdown

@@ -0,0 +1,63 @@
+---
+layout: page
+title: "HomeKit"
+description: "Instructions how to setup the HomeKit component in Home Assistant."
+date: 2018-02-20 17:30
+sidebar: true
+comments: false
+sharing: true
+footer: true
+ha_category: Voice
+ha_release: 0.64
+logo: apple-homekit.png
+---
+
+The `HomeKit` component allows you to forward entities from Home Assistant to Apple `HomeKit`, so they could be controlled from Apple `Home` app and `Siri`.
+
+{% configuration %}
+  homekit:
+    description: HomeKit configuration.
+    required: true
+    type: map
+    keys:
+      pincode:
+        description: Pin code required during setup of HomeKit Home Assistant accessory. The format needs to be 'XXX-XX-XXX' where X is a number between 1 and 9.
+        required: false
+        type: string
+        default: '"123-45-678"'
+      port:
+        description: Port for the HomeKit extension.
+        required: false
+        type: int
+        default: 51826
+{% endconfiguration %}
+
+## {% linkable_title Setup %}
+
+To enable the `HomeKit` component in Home Assistant, add the following to your configuration file:
+
+```yaml
+# Example for HomeKit setup
+homekit:
+  pincode: '123-45-678'
+```
+
+<p class='note'>It is not recommended to choose '123-45-678' as your pin code!</p>
+
+After Home Assistant has started, all supported entities (see the [list](#supported-components) below which components are already integrated) will be exposed to `HomeKit`. To add them:
+1. Open the `Home` App.
+2. Choose `Add Accessory` and then `Don't Have a Code or Can't Scan?`.
+3. The `Home Assistant` Bridge should be listed there. Select it and follow the instructions to complete setup.
+
+After the setup is completed you should be able to control your Home Assistant components through `Home` and `Siri`.
+
+## {% linkable_title Supported Components %}
+
+The following components are currently supported:
+
+| Component | Type Name | Description |
+| --------- | --------- | ----------- |
+| cover | Window | All covers that support `set_cover_position`. |
+| sensor | TemperatureSensor | All sensors that have `Celsius` as their `unit_of_measurement`. |
+
+<p class='note'>Currently only devices that are setup when Home Assistant is starting can be exposed to `HomeKit`. This means that especially `Z-Wave` components are currently not supported, since they will be setup afterwards. We are working on a solution for this problem.</p>