Summary

Add a top-level link from README.md to docs/kcenon-system-layout.md so the standard is discoverable.

Part of #656. Depends on #658.

Why

• A standard nobody reads is not a standard
• The README is the entry point; one paragraph plus link is enough

Scope

1. Add a short section ("Layout Standard" or similar) under an existing logical heading (Architecture / Contributing / Development)
2. Link to docs/kcenon-system-layout.md with a one-sentence description

Acceptance Criteria

• README links to the standard
• Section is no more than one short paragraph
• No other README structural changes in this PR

Out of Scope

• Restructuring the README beyond the inserted section
• Any cross-repo coordination