Update CONTRIBUTING.md to clarify testing instructions.

[ayakut16]

Description

This PR updates the documentation to include an additional step for testing local changes using ./bin/mcp.
This aims to make it clearer how developers can verify their changes locally during development.

Type of change

• Documentation update

How Has This Been Tested?

Not applicable – documentation-only change. No code or functionality was modified.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works (Not applicable)
• New and existing unit tests pass locally with my changes (Not applicable)
• Any dependent changes have been merged and published in downstream modules (Not applicable)