[docs] very helpful listing code section.

[jamaluddinrumi]

i don't keep my eyes on vite docs, but today i'm just surprised.

✨it's nice to see filename title above the code with that beautiful appearance.

it eliminates ambiguity where the listing code shoud be put on (plus with perfect appearance).

will be nice to see that beautiful appearance in undocs based, say, nitro docs as well.

🙌kudos vite team!