Merge pull request #5599 from mwindower/master

Add slack channel for metal-stack

Author: k8s-ci-robot

communication/slack-config/channels.yaml

@@ -257,6 +257,7 @@ channels:
   - name: meetup-trondheim
   - name: meetup-tunisia
   - name: metacontroller
+  - name: metal-stack
   - name: metallb
   - name: metallb-dev
   - name: microk8s