Add https://docs.ultralytics.com/help/contributing

[glenn-jocher]

copilot:all

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Update to the YOLOv3 contribution guide link for better accessibility and clarity.

📊 Key Changes

• Updated the URL for the Contributing Guide to direct users to the Ultralytics documentation site.
• Made the same update across different language versions of the README (English and Chinese).

🎯 Purpose & Impact

• ✍️ Provides contributors with a more streamlined and comprehensive guide to start contributing to the YOLOv3 project.
• 🌐 Improves the contribution process by ensuring non-English speakers also have updated links in their language.
• 🚀 Potentially increases the quality and quantity of contributions by making it easier to understand how to contribute.