Added openhome documentation (#2107)

* Added openhome documentation

* PR comments; added Linn and added an image

source/_components/media_player.openhome.markdown

@@ -0,0 +1,25 @@
+---
+layout: page
+title: "Linn / Openhome"
+description: "Instructions how to integrate Linn Ds and Openhome renderers into Home Assistant."
+date: 2017-02-21 22:40
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: linn.png
+ha_category: Media Player
+featured: false
+ha_release: 0.39
+ha_iot_class: "Local Polling"
+---
+
+
+The `openhome` platform allows you to connect an [Openhome Compliant Renderer](https://www.openhome.org) to Home Assistant such as a [Linn Products Ltd](https://www.linn.co.uk) HiFi streamer. It will allow you to control media playback, volume, source and see the current playing item. Openhome devices should be discovered by using the [the discovery component](/components/discovery/), their device names are taken from the name of the room configured on the device. 
+
+```yaml
+# Example configuration.yaml entry
+discovery:
+media_player:
+  - platform: openhome
+```