fix : useWindowScroll hook's returning scrollTo function type error

[Programming-Seungwan]

fix #296

It was using type of like, (args: unknown) => void

So, using scrollTo function like scrollTo(200, 300) was making typescript error.

So, I fixed type like it.

  export function useWindowScroll(): [
    {
      x: number | null;
      y: number | null;
    },
    {
      (xCoord: number, yCoord: number): void;
      (options: ScrollToOptions): void;
    }
  ];

It is based on mdn references.