[auditbox] update api docs

[Gerivian]

Note

Docs updates for API search usage and response semantics

• Refines api.md search examples: shows combining parameters with & for action+patient, and introduces comma-separated multi-value token search (e.g., action=C,U)
• Clarifies getting-started/read-auditevents-using-api.md GET-by-ID behavior: 200 on success; body includes event data if found, otherwise empty

^{Written by Cursor Bugbot for commit 1b6f342. This will update automatically on new commits. Configure here.}