Copy rollershutter and garage_door docs to cover

Re: home-assistant/home-assistant#1949

source/_components/cover.scsgate.markdown

@@ -0,0 +1,35 @@
+---
+layout: page
+title: "SCSGate Cover"
+description: "Instructions how to integrate SCSGate motorized devices into Home Assistant."
+date: 2016-06-28 17:30
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: bus_scs.png
+ha_category: Cover
+---
+The SCSGate devices can control motorized covers connected to the BTicino
+MyHome system.
+
+To enable SCSGate covers in your installation, add the following to your
+`configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+cover:
+  platform: scsgate
+  devices:
+    living_room:
+      name: Living Room
+      scs_id: XXXXX
+```
+
+Configuration variables:
+
+- **devices** (*Required*): A list of devices with their name to use in the
+  frontend.
+
+**Known limitation:** it is not possible to know the current state of the
+cover.