docs: add Contributor's Guide

[Amank1412]

Add CONTRIBUTING.md guide

Added a comprehensive CONTRIBUTING.md file to help new contributors get started with the project. The guide includes:

• Introduction to CARE and prerequisites
• Setup instructions and learning resources
• Codebase structure overview
• Coding standards and commit guidelines
• Step-by-step contribution workflow
• Communication channels and support information

This will make it easier for new contributors to understand how to contribute to the project.

Fixes: #230

[areebahmeddd]

i don’t think this is necessary since this is already covered here:

https://docs.ohc.network/docs/contributing
https://docs.ohc.network/docs/faq

[Amank1412]

Got it, thanks for the clarification.

Since this is already covered in the docs, I’ll close the PR to avoid redundancy.