Added notes about the states (home-assistant#5432)

DubhAd · fabaff · commit b40ea4dd972c · 2018-05-26T09:38:38.000+02:00
* Added notes about the states

A common question is "what's the state of the device tracker", so I've added a summary

* Update link
diff --git a/source/_components/device_tracker.markdown b/source/_components/device_tracker.markdown
@@ -88,3 +88,7 @@ devicename:
 | `track`        | [uses platform setting]       | If  `yes`/`on`/`true` then the device will be tracked. Otherwise its location and state will not update. |
 | `hide_if_away` | False                         | If `yes`/`on`/`true` then the device will be hidden if it is not at home.                                |
 | `consider_home` | [uses platform setting]      | Seconds to wait till marking someone as not home after not being seen. Allows you to override the global `consider_home` setting from the platform configuration on a per device level.                                 |
+
+## {% linkable_title Device states %}
+
+The state of your tracked device will be `'home'` if it is in the [home zone](/components/zone#home-zone), detected by your network or Bluetooth based presence detection. If you're using a presence detection method that includes coordinates then when it's in a zone the state will be the name of the zone (in lower case). When a device isn't at home and isn't in any zone, the state will be `'not_home'`.
