Add --copy-files to build/dev scripts

[sandro-pasquali]

Hi!

It might be useful to mention in the docs that for JavaScript build/dev developers might want to update the package generated by https://github.com/vadimdemedes/create-ink-app/blob/main/templates/js/_package.json, and add --copy-files, eg:

  "scripts": {
    "build": "babel --out-dir=dist source --copy-files",
    "dev": "babel --out-dir=dist --watch source --copy-files",

I think it will surprise people if lookups fail for non-js files in their code, and they might not know how to carry non-compiled files over into their dist.