Added initial documentation to Ring.com sensor (#2203)

source/_components/sensor.ring.markdown

@@ -0,0 +1,40 @@
+---
+layout: page
+title: "Ring"
+description: "Instructions on how to integrate your Ring.com devices within Home Assistant."
+date: 2017-03-05 10:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: ring.png
+ha_category: Sensor
+ha_release: 0.40
+---
+
+The `ring` sensor allows you to integrate your [Ring.com](https://ring.com/) devices in Home Assistant.
+Currently it supports doorbells and external chimes only.
+
+To enable device linked in your [Ring.com](https://ring.com/) account, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: ring
+    username: USERNAME
+    password: PASSWORD
+    monitored_conditions:
+      - battery
+      - last_activity
+      - volume
+```
+
+Configuration variables:
+
+- **username** (*Required*): The username for accessing your Ring account.
+- **password** (*Required*): The password for accessing your Ring account.
+- **scan_interval** (*Optional*): Defines the update interval of the sensor in seconds. The default is 30 seconds.
+- **monitored_conditions** array (*Required*): Conditions to display in the frontend. The following conditions can be monitored.
+  - **battery**: Return the battery level from device
+  - **last_activity**: Return the timestamp from the last event captured by the Ring doorbell camera
+  - **volume**: Return the volume level from the device. Currently supported by external chimes and doorbells.