Document caching of static assets with adapter-static

[benmccann]

Describe the problem

All other adapters automatically cache static assets for you. adapter-static does not

Describe the proposed solution

Add docs stating that you need to cache the immutable directory and saying which headers to set

Alternatives considered

No response

Importance

nice to have

Additional Information

No response

[hyunbinseo]

If a static site has to be deployed to a specific supported platform (e.g. Cloudflare Pages), is it better to:

• Use @sveltejs/adapter-cloudflare
• Set export const prerender = true in the root +layout.ts file

If using a platform specific adapter fixes immutable assets' caching problem, maybe adding a warning on top of the adapter-static documentation is viable. I have experienced this problem before.