Add datadog component documentation (#2452)

source/_components/datadog.markdown

@@ -0,0 +1,41 @@
+---
+layout: page
+title: "Datadog"
+description: "Send data and events to Datadog."
+date: 2017-04-18 00:00
+sidebar: true
+comments: false
+sharing: true
+logo: datadog.png
+footer: true
+ha_category: "History"
+ha_release: 0.43
+---
+
+The `datadog` component sends all state changes to [Datadog](https://www.datadoghq.com/) using a [Datadog Agent](http://docs.datadoghq.com/guides/basic_agent_usage/).
+
+Datadog allows you to analyze, monitor, cross-reference and alert upon your data. You can use it to detect statistical anomalies, see graphs across multiple sources in real-time, send critical alerts to Slack, etc.
+
+<p class='img'>
+  <img src='{{site_root}}/images/screenshots/datadog-board-example.png' />
+</p>
+
+The component also sends events from the logbook into Datadog, allowing you to correlate these events with your data.
+
+<p class='img'>
+  <img src='{{site_root}}/images/screenshots/datadog-event-stream.png' />
+</p>
+
+To use the `datadog` component in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+datadog:
+```
+
+Configuration variables:
+
+- **host** (*Optional*): The IP address or hostname of your Datadog host, e.g. 192.168.1.23. Defaults to `localhost`.
+- **port** (*Optional*): Port to use. Defaults to 8125.
+- **prefix** (*Optional*): Prefix to use. Defaults to `hass`.
+- **rate** (*Optional*): The sample rate of UDP packets sent to Datadog. Defaults to 1.