docs(ssr): Fix `prefetchQuery()` function calls (#6428)

This is the correct signature for [prefetchQuery](https://tanstack.com/query/v4/docs/react/reference/QueryClient#queryclientprefetchquery): 

```js
await queryClient.prefetchQuery({ queryKey, queryFn })
```

I noticed the docs were using a slightly stale signature.

^(Thank you for building an amazing library.)