Annotation domain belongs to Kubernetes

[sftim]

I notice that this project uses the domain backup.kubernetes.io for annotations, such as backup.kubernetes.io/deltas.

The friendly thing to do is for the project to use its own domain (or, get the Kubernetes project to register an official annotation).

The bug here is that k8s-snapshot is using an unregistered annotation. You could switch to cloud.elsdoerfer.name/k8s-backup-deltas for example, or register a different domain and use that. Could be like k8s-snapshot.something.example/deltas.

It's OK to deprecate the old annotation and support it indefinitely; it's better to switch and document / recommend using the updated annotation though.