Improve Documentation on Contributing Process

# Documentation Improvement

## Description
The current README provides a good overview of the steps to contribute to the NativeBase Docs, but it could benefit from more detailed information regarding the development environment setup and testing process.

## Suggested Improvements
1. **Environment Setup:** Add information on prerequisites needed for the setup (Node.js version, package manager, etc.).
2. **Testing Changes:** Include a section that explains how to run tests, what types of tests are available (if any), and how to interpret the results after running `yarn build` and `yarn start`.
3. **Common Issues:** A subsection addressing common pitfalls encountered during setup or contribution would help new contributors troubleshoot effectively.

By improving these areas, we can ensure that new contributors have a smoother onboarding experience!