[Doc] Add a note about the server route parameter

[soullivaneuh]

On this doc: https://sapper.svelte.dev/docs#Server_routes

You say:

Each function receives HTTP request and response objects as arguments, plus a next function.

But I don't see anything on the doc of what is in the request/response and which method I can call.

If this is the right from the polka server, adding some links would be very nice. 👍

[soullivaneuh]

I supposed it's related to this? https://expressjs.com/fr/api.html#req

[benmccann]

Yes, that's right. PRs welcome if you'd like to update it

https://github.com/sveltejs/sapper/tree/master/site/content/docs

[Conduitry]

In the current default template it's https://github.com/lukeed/polka - I'm not sure we want to send people on an adventure to read a bunch of Express docs that probably aren't relevant to them. Perhaps we can just link to the Node docs on req and res, since those are the base objects that both Express and Polka build upon.