Create README.md for delete-repository-event

Author: MikeNwin

hooks/ruby/delete-repository-event/README.md

@@ -0,0 +1,22 @@
+# :x: Delete Repository Event
+
+### :dart: Purpose
+
+This Ruby server:
+
+1. Listens for when a [repository is deleted](https://help.github.com/enterprise/user/articles/deleting-a-repository/) using the [`repository`](https://developer.github.com/enterprise/v3/activity/events/types/#repositoryevent) event and `deleted` action.
+
+2. Creates an issue in `GITHUB_NOTIFICATION_REPOSITORY` as a notification and includes: 
+
+    - a link to restore the repository
+    - the delete repository payload
+
+### :gear: Configuration
+
+1. See the [webhooks](https://developer.github.com/webhooks/) documentation for information on how to [create webhooks](https://developer.github.com/webhooks/creating/) and [configure your server](https://developer.github.com/webhooks/configuring/).
+
+2. Set the following required environment variables:
+
+    - `GITHUB_HOST` - the domain of the GitHub Enterprise instance. e.g. github.example.com
+    - `GITHUB_API_TOKEN` - a [Personal Access Token](https://help.github.com/enterprise/user/articles/creating-a-personal-access-token-for-the-command-line/) that has the ability to create an issue in the notification repository
+    - `GITHUB_NOTIFICATION_REPOSITORY` - the repository in which to create the nofication issue. e.g. github.example.com/administrative-notifications