publish Type declaration

[paulgirard]

Hi there,

Thanks a lot for your lib.
I am using it in a TypeScript project. I can see you are using TypeScript too but unfortunately you don't publish the type declaration of your API.
It's a shame as users can't benefit form your typings and have to redeclare those locally in a biiif.d.ts with :

declare module "bifff" {
  type build = (dir: string, url: string, virtualName?: string) => Promise<void>;
}

You might consider adding typescript declaration in your build.