slack: add channels for projects devspace and kiosk (#4806)

* Update channels.yaml

* Update channels.yaml

Author: Lukas Gentele

communication/slack-config/channels.yaml

@@ -55,6 +55,7 @@ channels:
   - name: csi-secrets-store #this channel is for secrets-store-csi-driver which is a subproject of sig-auth
   - name: de-events
   - name: de-users
+  - name: devspace
   - name: devstats
   - name: dexidp
   - name: digitalocean-k8s
@@ -130,6 +131,7 @@ channels:
   - name: keel
   - name: kiam
   - name: kind
+  - name: kiosk
   - name: kcli
   - name: klog
   - name: knative