Update README.zh-CN.md

[glenn-jocher]

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🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Update to the Chinese README with new YOLOv8 anniversary link and banner.

📊 Key Changes

• Updated banner image source URL for better relevancy.
• Added an alternate text "YOLO Vision banner" to the banner image for improved web accessibility.

🎯 Purpose & Impact

• The updated link now points to a blog post celebrating the one-year anniversary of YOLOv8, offering insights into its advancements and innovations.
• Users will benefit from the latest information about YOLOv8 directly from the project README.
• Improved accessibility with alt text helps visually impaired users understand the content of images, aligning with web content accessibility guidelines.