[Suggestion]: clarify behaviour of ref callbacks

Summary

The described behaviour for ref callbacks with null as an argument is ambiguous.

Page

https://react.dev/reference/react-dom/components/common#ref-callback

Details

From https://react.dev/reference/react-dom/components/common#ref-callback:

React will also call your ref callback whenever you pass a different ref callback. In the above example, (node) => { ... } is a different function on every render. When your component re-renders, the previous function will be called with null as the argument, and the next function will be called with the DOM node.

If I understand correctly, the emphasised sentenced is not correct when the ref callback returns a clean up function, as is the case in the referenced example. This needs to be clarified.

There is a note later on which helps a bit, but I still think this sentence could be made clearer so it makes sense in isolation.

Reduced test case to confirm this behaviour: https://stackblitz.com/edit/vitejs-vite-2r9rn6m2?file=src%2FApp.tsx&terminal=dev

Bắt đầu với phần ref-callback trên trang react.dev được liên kết và xem xét test case StackBlitz rút gọn để xác minh hành vi được mô tả. Làm rõ câu được đánh dấu để câu này vẫn chính xác khi callback trả về một hàm cleanup, đồng thời đảm bảo cách diễn đạt có ý nghĩa mà không phụ thuộc vào ghi chú ở phần sau.