Improve --local_rank arg comment

[pourmand1376]

Hi,
It took me to a while to understand why this parameter exists and what it does. I thought maybe adding this to help string would be a good idea.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Improvement in clarity for the Distributed Data Parallel (DDP) command-line argument description.

📊 Key Changes

• Modified the help description for the --local_rank argument in the training script's argument parser.

🎯 Purpose & Impact

• 🎓 Enhanced clarity: The new help text for the --local_rank argument makes it clear that it is used for automatic configuration in multi-GPU setups with Distributed Data Parallel (DDP).
• 🔄 Minimal impact on end-users: This change mainly affects user understanding; it does not impact the script's functionality. It's particularly helpful for developers or users working with multi-GPU training configurations.

[github-actions]

👋 Hello @pourmand1376, thank you for submitting a YOLOv5 🚀 PR! To allow your work to be integrated as seamlessly as possible, we advise you to:

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[glenn-jocher]

@pourmand1376 PR is merged. I've tried to strike the right balance here between explanatory comments and concise code.

Thank you for your contributions to YOLOv5 🚀 and Vision AI ⭐

[pourmand1376]

Thanks for reviewing.

I think we need a wiki to explain this stuff more concisely. Now, the explanation for each parameter is simply not enough.

[glenn-jocher]

@pourmand1376 yes, agreed we need more documentation.

We should be updating our docs at docs.ultralytics.com in the future with more detailed explanations.

@AyushExel FYI

[AyushExel]

@glenn-jocher I'm putting docs on the agenda of our discussion for Saturday

[glenn-jocher]

@AyushExel yes good idea