Improve CONTRIBUTING.md for Web-dev-mini-projects #950

The current CONTRIBUTING.md explains how to contribute, but it could benefit from examples and a step-by-step checklist for beginners.

Suggestions

1. Add a sample project folder structure

   • Include index.html, style.css, script.js, and README.md.

2. Clarify branch naming and PR process

   • Give an example branch name and a simple PR title template.

3. Add a checklist for first-time contributors

   • Fork → Clone → Add Project → Test → Commit → Push → PR

4. Optional: Visuals

   • Screenshots or GIFs can guide beginners on how to structure files.

Improving the CONTRIBUTING.md will make it easier for new contributors to follow and increase engagement.