[Typo]: Remove from menu for non-existent pages

Summary

I clicked on the menu because I was curious about the router, but the page was not provided.

Page

https://18.react.dev/learn/creating-a-react-app#react-router-v7

Details

I clicked on the menu because I was curious about the router, but the page was not provided.

If it's a non-existent page, I think it would be better if it wasn't shown at all in the menu.

I think it's a problem when I choose version 18, but not in version 19.
https://react.dev/learn/creating-a-react-app#react-router-v7

比較回報的 Creating a React App 頁面中 React Router v7 連結附近的版本 18 和版本 19 文件選單。找出指向無法使用頁面的選單項目，將其從版本 18 選單中移除，並確認不存在的連結不再出現。