[steiza]

Summary

Completes #4470?? I think this is the last Cosign command users have asked about protobuf bundle support.

It will print out:

Command "copy" is deprecated, there are several options you can use instead:
  - "oras copy -r" will copy images and referring artifacts
  - "cosign save" to write to disk, followed by "cosign load" for a new registry
  - "cosign download" followed by "cosign attach" to just copy the bundle

Release Note

• Deprecated cosign copy; if you are using the new protobuf bundle format we recommend you use oras copy -r instead, which will copy the image along with any referring artifacts

Documentation

N/A