What is the "module" package.json field for? : <p>I've seen some npm packages (<a href="https://github.com/vuejs/vue/blob/v2.2.2/package.json#L6" rel="noreferrer">vue for example</a>) have a <code>pkg.module</code> field in their package.json. Is <code>"module"</code> an official npm property or is this a convention of some kind? Is there documentation for this somewhere? What's it for? esnext path? Unbundled module path?</p>
