Add README App section

[glenn-jocher]

@AyushExel @pderrenger this should increase our app visibility per #10431

Signed-off-by: Glenn Jocher glenn.jocher@ultralytics.com

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Introducing the Ultralytics Mobile App for running YOLOv5 models on iOS and Android devices! 📱

📊 Key Changes

• Added a new section in the README for the Ultralytics Mobile App.
• Included a link to download the app and an appealing visual to showcase it.

🎯 Purpose & Impact

• 🚀 Purpose: This update is aimed to extend the accessibility of YOLOv5 models, allowing users to run them directly on their mobile devices.
• 🌍 Impact: Users can now experiment with and deploy YOLOv5 models on-the-go, making machine learning more accessible and convenient for a wider audience.

[glenn-jocher]

@sergiossm PR to improve App visibility in YOLOv5