Add mqtt device tracker page

source/components/device_tracker.mqtt.markdown

@@ -0,0 +1,31 @@
+---
+layout: page
+title: "MQTT device tracker support"
+description: "Instructions how to integrate MQTT based trackers into Home Assistant."
+date: 2015-09-17 09:00
+sidebar: false
+comments: false
+sharing: true
+footer: true
+---
+
+<img src='/images/supported_brands/mqtt.png' class='brand pull-right' />
+Before this tracker allows the detection of devices which are able to send MQTT messages.
+
+```yaml
+# Example configuration.yaml entry
+device_tracker:
+  platform: mqtt
+  qos: 1
+  devices:
+    paulus_oneplus: /location/paulus
+    annetherese_n4: /location/annetherese
+```
+
+Configuration variables:
+
+- **qos** (*Required*): Quality of service, default to 0.
+- **devices** (*Required*): Array of devices to track.
+  - **'device_name'** (*Required*): Name to use followed by the topic.
+
+See the [device tracker component page](/components/device_tracker.html) for instructions how to configure the people to be tracked.