Add README example finding summary

[stacknil]

Summary

• Add a first-screen README Example Finding JSON snippet
• Use a documentation-reserved source IP and an explicit triage-not-attribution boundary
• Keep the example framed as a compact summary rather than the raw report schema

Validation

• git diff --check main...HEAD
• Privacy/security scan over the PR diff for local paths, private keys, common token prefixes, identity markers, and non-documentation IPv4 literals
• README-only change; CTest not run locally