Refactor S3 FIFO cache documentation for clarity and conciseness

- Streamlined module documentation to enhance readability and focus on key aspects of the S3 FIFO cache implementation.
- Updated architectural diagrams and descriptions to reflect the current data structures and queue organization.
- Removed outdated sections and improved performance metrics presentation, aligning with Rust API Guidelines.
- Ensured that the documentation accurately represents the cache's behavior and usage patterns.

Author: TKorr