Added note about instant updates (home-assistant#5308)

DubhAd · fabaff · commit e1ccd79776e7 · 2018-05-08T09:28:16.000+02:00
Added note about instant updates and the Controlled command classes that are required for it to work.
diff --git a/source/_docs/z-wave.markdown b/source/_docs/z-wave.markdown
@@ -37,3 +37,9 @@ There are 12 different regions for Z-Wave devices, which relates to the frequenc
 You'll now need to connect your [controller](/docs/z-wave/controllers/), [configure](/docs/z-wave/installation) the Z-Wave component, then [add some devices](/docs/z-wave/adding) using the [control panel](/docs/z-wave/control-panel). [This explains](/docs/z-wave/devices/) about devices, and how [entities are named](/docs/z-wave/entities).
 
 You can get more information on the [available services](/docs/z-wave/services/) and [events](/docs/z-wave/events/), what the [query stages](/docs/z-wave/query-stage) of battery powered devices are, as well as details on configuring [specific devices](/docs/z-wave/device-specific/).
+
+## {% linkable_title Instant status updates %}
+
+When you toggle a switch or control a light locally you may find that it takes some time for that to be reflected in Home Assistant. That's because Lutron had patents on the status updates using the *Hail* command class, the traditional way of allowing devices to tell the controller that something happened locally. The same result can be achieved through the *Association* command class, or *Central Scene* command class (though, *Central Scene* isn't [fully supported](https://github.com/OpenZWave/open-zwave/pull/1125) in OpenZWave). 
+
+If you search [the Z-Wave products database](http://products.z-wavealliance.org/) for your product and it lists one of those in the **Controlled** command classes (not the **Supported** command classes), then your device will be able to report state changes when they happen. If it doesn't then updates may either happen eventually, or you may need to (carefully) [enable polling](https://www.home-assistant.io/docs/z-wave/control-panel/#entities-of-this-node).
