doc: post-release doc update

Update the post-release install overlays update doc
to use the helper script

docs/Release-Process.md

@@ -223,9 +223,7 @@ The CoCo operator reference commit in the [versions.yaml](../src/cloud-api-adapt
 
 The changes on the overlay kustomization files should be reverted to start using the latest cloud-api-adaptor images again:
 ```
-pushd src/cloud-api-adaptor/install/overlays/
-for provider in aws azure ibmcloud ibmcloud-powervs libvirt vsphere; do cd ${provider}; kustomize edit set image cloud-api-adaptor=quay.io/confidential-containers/cloud-api-adaptor:latest; cd -; done
-popd
+./hack/release-helper.sh caa-image-tag latest
 ```
 
 The `CITATION.cff` needs to be updated with the dates from the release.