Fixes hydrateRoot link (#4775)

Fixes #4770

content/docs/reference-react-dom.md

@@ -108,7 +108,7 @@ If the optional callback is provided, it will be executed after the component is
 > and should be avoided because future versions of React may render components asynchronously in some cases. If you need a reference to the root `ReactComponent` instance, the preferred solution is to attach a
 > [callback ref](/docs/refs-and-the-dom.html#callback-refs) to the root element.
 >
-> Using `render()` to hydrate a server-rendered container is deprecated. Use [`hydrateRoot()`](#hydrateroot) instead.
+> Using `render()` to hydrate a server-rendered container is deprecated. Use [`hydrateRoot()`](/docs/react-dom-client.html#hydrateroot) instead.
 
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