Added Leviton Decora Smart Wi-Fi component documentation (#3021)

* Added Leviton Decora Smart Wi-Fi component documentation

* Update version

source/_components/light.decora_wifi.markdown

@@ -0,0 +1,37 @@
+---
+layout: page
+title: "Decora Wi-Fi"
+description: "Instructions on how to setup Leviton Decora Smart Wi-Fi switches/dimmers within Home Assistant."
+date: 2017-07-19 12:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+ha_category: Light
+ha_iot_class: "Local Polling"
+logo: leviton.png
+ha_release: 0.51
+---
+
+Support for [Leviton Decora Wi-Fi](http://www.leviton.com/en/products/lighting-controls/decora-smart-with-wifi) dimmers/switches.
+
+Supported devices (tested):
+
+- [DW6HD1-BZ](https://www.leviton.com/en/products/dw6hd) (Decora Smart Wi-Fi 600W Dimmer)
+
+To enable these lights, add the following lines to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+light:
+  - platform: decora_wifi
+    username: my_leviton_user_email@email.com
+    password: my_leviton_password
+```
+
+Configuration variables:
+
+- **username** (*Required*): Your "My Leviton" app email address/user name.
+- **password** (*Required*): Your "My Leviton" app password.
+
+