Problem

docs/examples/hello-world.md only teaches pn run android / pn run ios (lines 8 and 52-66), while the example's own examples/hello-world/README.md and docs/getting-started.md both lead with pn preview as the fastest iteration loop. Readers who land on the example page first never learn that they can try the app without an emulator or simulator.

Suggested fix

Add a short "Preview on desktop" section to docs/examples/hello-world.md before the device-run instructions, showing pn preview and linking to the desktop preview guide (docs/guides/desktop-preview.md). The wording in examples/hello-world/README.md is a good starting point, including its note about installing the example's [requirements].packages locally first.

Verification

Run mkdocs build --strict.

Suggested commit message

docs(mkdocs): mention pn preview in the hello-world example