Add documentation for the notify.group platform

source/_components/notify.group.markdown

@@ -0,0 +1,36 @@
+---
+layout: page
+title: "Notify Group"
+description: "Instructions how to setup the notify group platform."
+date: 2016-08-18 00:12
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: home-assistant.png
+ha_category: Notifications
+ha_release: 0.26
+---
+
+The `group` notification platform allows you to combine multiple `notify` platforms into a single service.
+
+To use this notification platform in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+notify:
+  name: MyDevices
+  platform: group
+  services:
+    - service: html5
+      data:
+        target: "macbook"
+    - service: html5_nexus
+```
+
+Configuration variables:
+
+- **name** (*Required*): Setting the parameter `name` sets the name of the group.
+- **services** (*Required*): A list of all the services to be included in the group.
+  - **service** (*Required*): The service part of an entity ID, i.e. if you use `notify.html5` normally, just put `html5`.
+  - **data** (*Optional*): A dictonary containing parameters to add to all notify payloads. This can be anything that is valid to use in a payload, such as `data`, `message`, `target`, `title`.