Update W&B README

[glenn-jocher]

@AyushExel I've updated all of the images for better darkmode transparency and brought Environments and Status up to speed with the other tutorials. Any other changes you'd like to make before I merge?

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Enhancements to YOLOv5 documentation for Weights & Biases integration.

📊 Key Changes

• Improved readability of the Weights & Biases (W&B) documentation markdown.
• Added visual examples and updated screenshots to reflect the current state.
• Provided direct access links to YOLOv5 Colab and Kaggle notebook environments.
• Updated information on Continuous Integration (CI) status display.

🎯 Purpose & Impact

• Usability: Simplified navigation through a cleaner markdown structure.
• Clarity: Clearer and more current visuals aid user understanding of the W&B dashboard and reporting tools.
• Accessibility: Immediate access to YOLOv5's notebooks encourages quick start on Colab and Kaggle.
• Transparency: Displays CI status to keep users informed about the health of the YOLOv5 codebase.

[AyushExel]

Looks good. thanks