improve CRD schema descriptions for kubectl explain usability

[lhajouji]

Summary

When using kubectl explain on Argo Rollouts resources like AnalysisRun or Rollout, most fields — especially spec and status — have no description or very minimal info. This makes it hard to understand what each field does without checking the docs or source code.

It would be great to add proper descriptions in the Go structs so that the CRD schema provides more useful output through kubectl explain.

Use Cases

• Get quick help directly in the terminal without switching to docs
• Make it easier for new users to understand the structure of Argo Rollouts objects
• Improve clarity for teams writing manifests or automating deployments

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