Merge pull request #8619 from richardcase/capi_wg_mp_slack

chore: add new slack channel for CAPI working group

Author: k8s-ci-robot

communication/slack-config/channels.yaml

@@ -85,6 +85,7 @@ channels:
   - name: cluster-api-proxmox
   - name: cluster-api-release
   - name: cluster-api-vsphere
+  - name: cluster-api-wg-machinepools
   - name: cn-dev
   - name: cn-events
   - name: cn-users