Add Stay link to resources in README

[nithishkesavarapu-code]

🧠 Visualize Data Structures & Algorithms in Real Time

Summary of your changes

📘 Description

This pull request adds a free interactive platform, staying.fun, which allows users to visualize Data Structures and Algorithms in real time.
The website provides step-by-step animations and interactive examples to help learners understand algorithmic processes and internal workings of data structures effectively.

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💡 Why is this valuable?

• Offers a hands-on way to learn complex DSA concepts visually.
• Enhances understanding through real-time simulations and animations.
• 100% free to access and easy to use for students, developers, and educators.

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🔓 How do we know it’s really free?

The platform staying.fun is publicly accessible and does not require any sign-up or payment to use its core visualization tools.

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✅ Checklist

• My change follows the Contributing Guidelines
• I have added only one new link to the list
• I have checked that the link does not already exist in the project
• I have sorted the link alphabetically under the related section