Initial docs for Västtrafik sensor (#1134)

* Initial docs for Västtrafik sensor

* vasttrafik key secret info

source/_components/sensor.vasttrafik.markdown

@@ -0,0 +1,46 @@
+---
+layout: page
+title: "Västtrafik Public Transport"
+description: "Instructions how to integrate timetable data for travelling in Sweden within Home Assistant."
+date: 2016-10-05 08:45
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: vasttrafik.png
+ha_category: Transport
+ha_iot_class: "Cloud Polling"
+ha_release: "0.30"
+---
+
+
+The `vasttrafik` sensor will provide you travelling details for the larger Göteborg area in Sweden from the [Västtrafik](https://vasttrafik.se/) public transportation service.
+
+You must create an application [here](https://developer.vasttrafik.se/portal/#/applications) to obtain a `key` and a `secret`.
+
+Add the data to your `configuration.yaml` file as shown in the example:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: vasttrafik
+    key: XXXXXXXXXXXXXXXXXXX
+    secret: YYYYYYYYYYYYYYYYY
+    departures:
+      - name: Mot järntorget
+        from: Musikvägen
+        heading: Järntorget
+        delay: 10
+```
+
+Configuration variables:
+
+- **key** (*Required*): The API key to access your Västtrafik account.
+- **secret** (*Required*): The API secret to access your Västtrafik account.
+- **departures** array (*Required*): List of travelling routes.
+  - **name** (*Optional*): Name of the route.
+  - **from** (*Optional*): The start station.
+  - **heading** (*Optional*): Direction of the travelling.
+  - **delay** (*Optional*): Delay in minutes.
+
+The data are coming from [Västtrafik](https://vasttrafik.se/).