Document validation artifact examples in the README

[human-again]

Goal

Make it easier for new users to understand the files Orbit writes after a run.

Suggested scope

• Add a short README section showing example artifact paths such as agent-result.json, evaluation.json, and review.json.
• Explain what each artifact proves.
• Keep the section concise and linked to existing demos where possible.

Acceptance criteria

• The README names the key artifacts and their purpose.
• The wording reinforces that validation evidence matters more than self-reported success.

[mg272011]

Hi! I can add a concise README section documenting Orbit's validation artifacts (agent-result.json, evaluation.json, review.json) and what each proves, linked to existing demos where possible. $5 after PR acceptance via PayPal/Cash App. If you're open to a paid micro-docs PR, I can do it today.