Tweaks to blocking route error message (#85191)
Makes it more clear that `<Suspense>` and "use cache" are separate
approaches for fixing the error, not requirements.
<img width="969" height="711" alt="Screenshot 2025-10-21 at 3 09 57 PM"
src="https://github.com/user-attachments/assets/34bd2efc-9fee-4aba-82eb-6b395663d765"
/>
