chore: defer cookie parsing to external package;

[lukeed]

@signalnerve Since our examples are each in a single file right now, this <Aside> seemed like the best alternative since there's no way to include a package.json for this specific example. (We can do this in the rework, of course)

Unless you meant that I should include a snippet showing package.json contents, like this:

// package.json
{
  "dependencies": {
    "cookie": "0.4.1",
    "worktop": "0.7.1"
  }
}

---

Closes #2074

[kristianfreeman]

good with it like this!