Add documentation for homekit controller component (#4966)

* Add documentation for homekit controller component

* Update docs to match the implementation

* ⬆️ ha_release

* ✏️ Language tweak

* ⬆️ ha_release

* ⬆️ ha_release

source/_components/homekit_controller.markdown

@@ -0,0 +1,31 @@
+---
+layout: page
+title: "HomeKit controller support"
+description: "Instructions how to integrate your HomeKit devices within Home Assistant."
+date: 2018-03-19 21:04
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: apple-homekit.png
+ha_category: Hub
+ha_release: 0.68
+ha_iot_class: "Local Polling"
+---
+
+[HomeKit](https://developer.apple.com/homekit/) controller integration for Home Assistant allows you to connect HomeKit accessories to Home Assistant. This component should not be confused with the [HomeKit](homekit) component, which allows you to control Home Assistant devices via HomeKit.
+
+There is currently support for the following device types within Home Assistant:
+
+- [Light](../light.homekit_controller)
+- [Switch](../switch.homekit_controller)
+
+The component will be automatically configured if the [`discovery:`](components/discovery/) component is enabled and an enable entry added for HomeKit:
+
+```yaml
+discovery:
+  enable:
+    - homekit
+```
+
+For each detected HomeKit accessory, a configuration prompt will appear in the web front end. Use this to provide the HomeKit PIN.