docs(ssr): Hydration caveat for Next.js' rewrites (#3209)

Adds a small section for a caveat about hydration when using some specific feature/configuration of Next.js

Author: bennettdams

docs/src/pages/guides/ssr.md

@@ -107,6 +107,12 @@ function Posts() {
 
 As demonstrated, it's fine to prefetch some queries and let others fetch on the queryClient. This means you can control what content server renders or not by adding or removing `prefetchQuery` for a specific query.
 
+### Caveat for Next.js rewrites
+
+There's a catch if you're using [Next.js' rewrites feature](https://nextjs.org/docs/api-reference/next.config.js/rewrites) together with [Automatic Static Optimization](https://nextjs.org/docs/advanced-features/automatic-static-optimization) or `getStaticProps`: It will cause a second hydration by React Query. That's because [Next.js needs to ensure that they parse the rewrites](https://nextjs.org/docs/api-reference/next.config.js/rewrites#rewrite-parameters) on the client and collect any params after hydration so that they can be provided in `router.query`.
+
+The result is missing referential equality for all the hydration data, which for example triggers whereever your data is used as props of components or in the dependency array of `useEffect`s/`useMemo`s.
+
 ## Using Other Frameworks or Custom SSR Frameworks
 
 This guide is at-best, a high level overview of how SSR with React Query should work. Your mileage may vary since there are many different possible setups for SSR.