docs: update pages automatic static optimization rendering page (#72545)
## Improving Documentation
I just add **Good to know** to below path note which was in a block but
not add the tag.
> Pages > Rendering > Automatic Static Optimization
**Before:**
> Statically generated pages are still reactive: Next.js will hydrate
your application client-side to give it full interactivity.
**Now:**
> **Good to know:** Statically generated pages are still reactive.
Next.js will hydrate your application client-side to give it full
interactivity.
Co-authored-by: Sam Ko <sam@vercel.com>