Add Three Axis Sensor docs (home-assistant#8879)

andrewsayre · frenck · commit d52fb948b4fe · 2019-03-11T20:08:31.000+01:00
diff --git a/source/_components/smartthings.markdown b/source/_components/smartthings.markdown
@@ -267,6 +267,7 @@ The SmartThings Sensor platform lets your view devices that have sensor-related
 | [`thermostatMode`](https://smartthings.developer.samsung.com/develop/api-ref/capabilities.html#Thermostat-Mode)                         | `thermostatMode`
 | [`thermostatOperatingState`](https://smartthings.developer.samsung.com/develop/api-ref/capabilities.html#Thermostat-Operating-State)    | `thermostatOperatingState`
 | [`thermostatSetpoint`](https://smartthings.developer.samsung.com/develop/api-ref/capabilities.html#Thermostat-Setpoint)                 | `thermostatSetpoint`
+| [`threeAxis`](https://docs.smartthings.com/en/latest/capabilities-reference.html#three-axis)                                            | `threeAxis` (as discrete sensors `X`, `Y` and `Z`)
 | [`tvChannel`](https://smartthings.developer.samsung.com/develop/api-ref/capabilities.html#Tv-Channel)                                   | `tvChannel`
 | [`tvocMeasurement`](https://smartthings.developer.samsung.com/develop/api-ref/capabilities.html#Tvoc-Measurement)                       | `tvocLevel`
 | [`ultravioletIndex`](https://smartthings.developer.samsung.com/develop/api-ref/capabilities.html#Ultraviolet-Index)                     | `ultravioletIndex`
