Add channel for Kubernetes Edinburgh Meetup Group

Add a dedicated Slack channel for use by members of the Kubernetes
Edinburgh Meetup Group, to be able to discuss and coordinate things such
as topics for future events.

communication/slack-config/channels.yaml

@@ -186,6 +186,7 @@ channels:
   - name: meetup-bordeaux
   - name: meetup-boston
   - name: meetup-dfw
+  - name: meetup-edinburgh
   - name: meetup-guatemala
   - name: meetup-hannover
   - name: meetup-hongkong