add forecast sensor page

source/components/sensor.forecast.markdown

@@ -0,0 +1,38 @@
+---
+layout: page
+title: "Forecast.io support"
+description: "Instructions how to integrate Forecast.io within Home Assistant."
+date: 2015-04-25 9:06
+sidebar: false
+comments: false
+sharing: true
+footer: true
+---
+
+<img src='/images/supported_brands/weather-few-clouds.png' class='brand pull-right' />
+The forecast platform uses the [Forecast.io](https://forecast.io/) web service as a source for meteorological data for your location. 
+
+You need an API key which is free but requires a [registration](https://developer.forecast.io/register).
+
+To add Forecast.io to your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  platform: forecast
+  api_key: YOUR_APP_KEY
+  monitored_conditions:
+    - summary
+    - precip_type
+    - precip_intensity
+    - temperature
+    - dew_point
+    - wind_speed
+    - wind_bearing
+    - cloud_cover
+    - humidity
+    - pressure
+    - visibility
+    - ozone
+```
+Details about the API are available in the (Forecast.io documentation)[https://developer.forecast.io/docs/v2].