[Suggestion]: Make clear why Ref was used in the third solution

Summary

The solution for the third challenge, "Fix debouncing," does not require a Ref. Moving the let timeoutID; to the top inside the DebouncedButton component will fix the debouncing. Either point this out in the explanation or make it re-render so the solution requires Ref.

Page

https://react.dev/learn/referencing-values-with-refs

Details

Since code example does not use State, there's no re-rendering, and so there's no need to use Ref to remember anything across re-renders. The page mentions that Refs are not used often; although future-proof, I think the example should only use Ref when necessary.

「Referencing Values with Refs」ページから始めて、3つ目のチャレンジ「Fix debouncing」を、その説明と解答を含めて確認します。ドキュメントで Ref を使う理由が説明されているか、または再レンダリングによって Ref が必要になるように例が変更されていれば完了です。レンダリングされたページとチャレンジの文言を確認してください。