docs: add Kubernetes audit log guide

[floze-the-genius]

Closes #13.

Summary

• add a Kubernetes API audit-log guide using current LynxFlow v2 syntax
• show how to identify anonymous requests and summarize source IPs and resources
• count distinct auditID values after expanding sourceIPs so proxy chains do not inflate request totals
• add a failed-request summary and document the trust limits of client-supplied fields
• add the guide to the docs sidebar

Validation

• built the current CLI and ran both documented queries against a three-event Kubernetes audit JSONL fixture
• npm run build in docs/site
• npm run typecheck in docs/site
• go vet ./...
• make docs-check-shippers

[OrlovEvgeny]

Thank you for contributing!