Some relevant details are missing in the documentation

I had some issues while following the docs and propose to add these relevant details:

The Info.plist in Xcode requires not only the background modes but also the labels as identifiers as information:

In the AppDelegate.swift file, an import statement must be added:

If relevant, location usage descriptions must be added to the Info.plist:

If the event handler return anything with `resolve()` it must be a proper JS object: