feat(hyperlink): added a hyperlink to Node in README.md file (#28940)

As a fellow beginner to React, I didn't even know React runs on top of
Node when I started.

So, some beginners might get confused about what is Node and how to find
details about it or how to download it.

So, I thought to add a hyperlink to Node replacing the word Node in the
README.md file. I think this might be a valuable contribution.

- Januda