Improve README documentation and structure

[Dark-Brain07]

Summary

This PR updates and improves the project’s README by providing clearer structure, modern formatting, and better explanations of the repository’s purpose, validation rules, examples, and contribution workflow.
The goal is to make the documentation easier for new contributors, integrators, and ecosystem developers to understand and reference.

Improvements Included

• Rewrites README for improved clarity and organization
• Enhances formatting, icons section, L2 parent structure explanation, constraints, and usage examples
• Adds clearer step-by-step PR contribution guidance
• Consolidates ecosystem references and tools
• Preserves all technical details while making them more readable

Why This Is Useful

A more readable README helps:

• Contributors avoid CI issues
• New chain integrations stay consistent
• Developers discover available tools and ecosystem support
• Users understand constraints such as chainId uniqueness and IPFS rules

Additional Notes

This PR does not change any chain definitions, code, or validation logic—only documentation.
No schema or data changes are introduced.

Ready for review. 🚀