Update JSON response

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Enhancement of the YOLOv5 Flask REST API documentation with JSON response formatting.

📊 Key Changes

• Clarified the API documentation in the README to indicate the YOLOv5 model reference from PyTorch Hub.
• Updated the model inference results section to illustrate the JSON response format used by the API.
• Inference results now include additional geometrical details such as height, width, xcenter, and ycenter for the detected objects.

🎯 Purpose & Impact

• ✅ Provides a clearer understanding of the API and its usage for developers integrating YOLOv5 into their applications.
• ✅ The JSON format in the documentation offers better readability and can help developers parse the results more efficiently.
• ✅ The added geometric information for detected objects allows for more precise post-processing and usage in various applications such as tracking or analysis software.