Deprecated instructions

https://github.com/argoproj/argocd-example-apps/blob/4773b9f1f8fd425f84174c338012771c4e9a989c/plugins/kustomized-helm/README.md?plain=1#L8

Configuring config management plugins via config-cm is removed. Instructions here are no longer valid. See:
https://argo-cd.readthedocs.io/en/stable/operator-manual/config-management-plugins/#migrating-from-argocd-cm-plugins