Worked on the apache/iceberg repository to enhance user onboarding by improving documentation for environment-based configuration in the iceberg-rest-fixture module. Focused on clarifying how CATALOG_* environment variables map to Iceberg configuration, the contribution detailed translation rules and provided practical examples for overriding catalog names. Using Markdown and leveraging skills in documentation and environment configuration, the update explained default behaviors, such as the in-memory SQLite fallback when certain variables are unset. This docs-only change aligned with existing documentation standards, aiming to reduce configuration-related support and make setup processes more transparent for end-users without introducing any code modifications or bug fixes.