Update README with improved mapping description

[squid-protocol]

Description of Structural Changes

Visual Observatory Testing

• I tested the output JSON on GitGalaxy.io OR the Airgap Observatory.
• Flexbox constraints, HUD elements, and 3D rendering remain intact.

The Differential Scan Acknowledgement

• I understand that my PR will be subjected to a Full Differential Scan.
• I have provided the link to the specific repository this PR addresses so it can be tested alongside the 80-repo calibrated baseline.
• I believe these changes will measurably improve the engine's Accuracy, Speed, Utility, or Ethos without causing regressions.