Fix app store URL

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Improvement of App Store link in the README for enhanced user navigation.

📊 Key Changes

• Updated the app store link in the README.md.
• Ensured that the link directs users to the correct app page.

🎯 Purpose & Impact

• Purpose: To correct a previously incorrect or outdated link that pointed to Xcode instead of the Ultralytics YOLO iOS App, making it easier for users to find and download the app.
• Impact: Enhances user experience by providing a direct and accurate link, helping to increase visibility and accessibility of the Ultralytics YOLO iOS App for potential users.