v3.2.1 - Documentation fixes

Fixed

• Corrected a dead link in the API endpoints guide that pointed at a non-existent prometheus.md; it now links to the Prometheus integration guide under advanced-usage/.

Changed

• Moved internal planning notes out of the published docs/ tree and added a requirements page so the documentation renders cleanly on the site.
• Bumped the cboxdk/laravel-telemetry dev requirement.