No Declarative Plugins anymore! - And documentation is not reflecting newest version for CMP

CMP in configmap is deprecated since version 2.5.

https://argo-cd.readthedocs.io/en/stable/operator-manual/upgrading/2.4-2.5/#argocd-cm-plugins-cmps-are-deprecated

Documentation example is not reflecting newest version:
https://github.com/argoproj/argocd-example-apps/blob/53e28ff20cc530b9ada2173fbbd64d48338583ba/plugins/kustomized-helm/README.md?plain=1#L11

https://argo-cd.readthedocs.io/en/stable/operator-manual/config-management-plugins/

For example we use but this simple configuration will not work anymore in the future.
```yaml
configManagementPlugins: |
- name: kustomize-build-with-helm
generate:
command: [ "sh", "-c" ]
args: [ "kustomize build --enable-helm" ]
```

Start with the linked plugins/kustomized-helm/README.md example and the Argo CD configuration-management-plugins documentation, then compare them with the linked 2.4–2.5 upgrade guidance. Update the documented example so it no longer relies on deprecated configMap declarative plugins, and verify that the referenced documentation consistently describes the supported configuration.

Written by the indexing model from the issue text.