Merge pull request #8038 from skoved/kubearchive-channel

add kubearchive slack channel

Author: k8s-ci-robot

communication/slack-config/channels.yaml

@@ -265,6 +265,7 @@ channels:
   - name: kubeadm
   - name: kubeadm-cn
   - name: kubeapps
+  - name: kubearchive
   - name: kubebuilder
   - name: kubecon
   - name: kubecfg