TypeScript support

[wojtekmaj]

Hey,
just wanted to share these typings I created:

declare module 'fetch-throttle' {
  function throttledFetch(
    input: RequestInfo | URL,
    init?: RequestInit
  ): Promise<Response>;

  const throttle = (fetch: fetch, calls: number, milliseconds: number) =>
    throttledFetch;

  export default throttle;
}

feel free to add it to your repo & ship if you feel like it, to make it easier for TypeScript users to use the library.