Replace React Redux recipe with Redux's recipe

[nickserv]

@MatanBobi has updated Redux's examples for Testing Library based on our recipe, and I think it would be easier to maintain the recipe by keeping it in one place in Redux (which has additional testing information) and redirecting from our existing page.

History: #570 (comment)

[nickserv]

I had to keep the Markdown file for this page but replace it with a stub so Docusaurus would still keep it in the sidebar. This should work with Netlify redirects, but please let me know if there's a better way.

[MatanBobi]

This one is tricky, not that I think of a different way to do it but if the anchor connected-components will be removed we'll just redirect to the page (not that bad) but if the name of the markdown file will change we will have a broken link here.
I can't think of a different way to do it though..

[nickserv]

Yea I don't think there's a way to fully avoid that issue, though it seems like Redux should be keeping the recipe URLs in place even with its doc reworks. I'll keep try to track of it just in case, and I'll update the heading anchor if reduxjs/redux#3876 is merged.

[nickserv]

The redirect is broken and will be fixed in #598.

I'll keep this merged since the link still helps reduce duplication and it's just one extra click without a redirect.