docs: added managed template to release docs
2. `./out/clusterawsadm-linux-amd64`
3. `./out/infrastructure-components.yaml`
4. `./templates/cluster-template.yaml`
+ 5. `./templates/cluster-template-managed.yaml`
9. Perform the [image promotion process](https://github.com/kubernetes/k8s.io/tree/master/k8s.gcr.io#image-promoter).
The staging repository is at https://console.cloud.google.com/gcr/images/k8s-staging-cluster-api-aws/GLOBAL. Be
sure to choose the top level `cluster-api-aws-controller`, which will provide the multi-arch manifest, rather than one for a specific architecture.
