Updating notifications docs for slack.

docs/build-configuration/notifications.md

@@ -6,11 +6,35 @@ permalink: /build/notifications/
 published: true
 ---
 
-Enabling notifications from Probo allows you to be automatically informed about your builds' status and completion. Currently, Probo supports webhook  `POST` notifications, but will soon support HipChat and Slack notifications as well.
+Enabling notifications in your Probo Build allows you to be automatically informed about your builds' status and completion. Currently, Probo supports webhook  `POST` notifications, and Slack notifications through a custom Slack app.
+
+## Slack notifications
+
+Probo now supports Slack notifications for your builds using a [custom Slack app](https://api.slack.com/apps/new) with an [Incoming Webhook](https://api.slack.com/incoming-webhooks) activated. 
+
+Receive slack notifications about your Probo builds by adding a `notifications` key to your `.probo.yaml` file. Within this `notifications` key, add a `slack` key containing a `webhook` key. Then add the webhook for your custom Slack app within the `webhook` key. You can add a single webhook URL or multiple webhook URLs for Slack notifications. See the following slack notifications examples for more information:
+
+### Examples
+
+{% highlight yaml %}
+notifications:
+  slack:
+    webhook:
+      - https://hooks.slack.com/services/EXAMPLE-1/WEBHOOK-1/PATH-1
+{% endhighlight %}
+
+{% highlight yaml %}
+notifications:
+  slack:
+    webhook:
+      - https://hooks.slack.com/services/EXAMPLE-1/WEBHOOK-1/PATH-1
+      - https://hooks.slack.com/services/EXAMPLE-2/WEBHOOK-2/PATH-2
+{% endhighlight %}
+
 
 ## Webhook notifications
 
-Get started with webbook notifications by adding a `notifications` key to your `.probo.yaml` file. Within this `notifications` key, add your webhook `POST` URL. You can add a single URL or multiple URLs. See the following examples for more information:
+Get started receiving webhook notifications for your Probo builds by adding a `notifications` key to your `.probo.yaml` file. Within this `notifications` key, add your webhook `POST` URL. You can add a single webhook URL or multiple webhook URLs for webhook notifications. See the following webhook notifications examples for more information:
 
 ### Examples