Update README.md

[glenn-jocher]

copilot:all

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Update to Ultralytics documentation build settings and badges display.

📊 Key Changes

• 🛠 Removed branch specification for the 'Check Broken Links' badge.
• ✂️ Simplified comments within the build steps for multi-language support.

🎯 Purpose & Impact

• ⚡ Improving clarity in the documentation's README, potentially leading to easier maintenance and understanding of the build process.
• 🧩 The badge adjustment ensures that the broken link check status is displayed for the default branch, enhancing accuracy for repository health indicators.
• 🌐 Streamlined build instructions for multi-language support, which can help future contributors in managing documentation updates.