Add Routing in React with Landing and About Pages

This PR sets up routing in a React application using React Router. It includes:

- A **Landing Page**
- An **About Page**
- Proper routing configuration to navigate between pages

### 🌟 Why You Should Try React!
If you've mastered HTML, CSS, and JavaScript, now is the perfect time to level up! 🚀 React makes building dynamic and interactive user interfaces much easier with:

✅ **Component-Based Architecture** – Reuse UI elements efficiently.
✅ **Effortless Routing** – Manage multiple pages seamlessly.
✅ **Fast & Scalable** – Optimized for performance and easy state management.

Jump into React today and take your web development skills to the next level! 💡✨

### **References:**
- [React Router Documentation](https://reactrouter.com/en/main)
- [React Official Documentation](https://react.dev/)