update url for React Hydration Documentation (#40883)

Docs point to old
__[hydrate()](https://reactjs.org/docs/react-dom.html#hydrate)__, which
had been replaced with
__[hydrateRoot()](https://reactjs.org/docs/react-dom-client.html#hydrateroot)__
as React 18 came:

> Note:
hydrate has been replaced with hydrateRoot in React 18. See
[hydrateRoot](https://reactjs.org/docs/react-dom-client.html#hydrateroot)
for more info.

From [react 18 docs](https://reactjs.org/docs/react-dom.html#hydrate).

errors/react-hydration-error.md

@@ -84,5 +84,5 @@ Common causes with css-in-js libraries:
 
 ### Useful Links
 
-- [React Hydration Documentation](https://reactjs.org/docs/react-dom.html#hydrate)
+- [React Hydration Documentation](https://reactjs.org/docs/react-dom-client.html#hydrateroot)
 - [Josh Comeau's article on React Hydration](https://www.joshwcomeau.com/react/the-perils-of-rehydration/)