Remove the React 15 support comment (#4648)
Remove the React 15 support comment (#4648)

Next.js supports React 15 / React-like alternatives that don’t have the `rehydrate` method (preact) again since Next.js 5+. It’s still not recommended to use React 15. But there’s no need to mention that here as this is the initial installation and we instruct the user to install the latest version of React.
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