Improve typing of third argument

[flyon]

Using typescript the third argument is called 'customStatic'. Which seems to indicate you can provide more statics, rather than provide a list of statics to avoid. I think the name can be more clear.

[eps1lon]

The types are part of https://github.com/DefinitelyTyped/DefinitelyTyped. Feel free to open a PR with a better name (and possibly docs explaining the intent).