Add Tibber documentation (#3497)

* Add Tibber documentation

* Update sensor.tibber.markdown

* Use new configuration style

source/_components/sensor.tibber.markdown

@@ -0,0 +1,33 @@
+---
+layout: page
+title: "Tibber"
+description: "Instructions how to integrate Tibber within Home Assistant."
+date: 2017-10-03 17:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: tibber.png
+ha_category: Sensor
+ha_release: 0.55
+ha_iot_class: "Cloud Polling"
+---
+
+
+The `tibber` sensor provides the current electricity price if you are a [Tibber](https://tibber.com/) customer.
+
+To add Tibber to your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: tibber
+    access_token: d1007ead2dc84a2b82f0de19451c5fb22112f7ae11d19bf2bedb224a003ff74a
+```
+
+{% configuration %}
+  access_token:
+    description: Go to [developer.tibber.com/](https://developer.tibber.com/) to get your API token.
+    required: true
+    type: string
+{% endconfiguration %}