Docs/optimize route group semantics

[WinmezzZ]

Summary

🤖[deprecated] Generated by Copilot at 97ed460

Updated the documentation of the routes feature in modern.js for both English and Chinese languages. Explained the new concepts and API of "Route Grouping" and "Route Flating" and their benefits for developers.

Details

🤖[deprecated] Generated by Copilot at 97ed460

• Rename and rewrite section titles and descriptions to clarify the features of using __ and $ in route files (link, link, link, link)
• Add sentences to highlight the benefit of using $ to create routes without layout components or deep directory levels (link, link)

Related Issue

Checklist

• I have added changeset via pnpm run change.
• I have updated the documentation.
• I have added tests to cover my changes.

[changeset-bot]

⚠️ No Changeset found

Latest commit: a80cd07

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[CLAassistant]

All committers have signed the CLA.

[KyrieLii]

@WinmezzZ 感谢贡献，不过请先签署下 CLA

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

[WinmezzZ]

done