Rationalize example naming and folder structure

Motivation: Current example files and folder structure may be inconsistent or unclear, making it harder for users to discover and navigate them.

This task aims to review and improve:

• Example file naming conventions
• Folder organization within the examples/ directory

The goal is to improve usability and ease of discovery, especially for newcomers exploring features via examples.

Note:

• Avoid naming example files after their corresponding src modules (e.g., led.rs, pca9685.rs) to improve file searchability in IDEs.
• Update the example README file
• Update the overall README file

Impact: No functional/API impact. This is a user / developer experience improvement.