Fixes tomcru#2

Add delay prop to HolyLoader component to delay the start of the progress bar.

* Add `delay` prop to `HolyLoaderProps` interface in `src/index.tsx` with a default value of 0.
* Modify `HolyLoader` component in `src/index.tsx` to use the `delay` prop to delay the start of the progress bar.
* Update `useEffect` hook in `src/index.tsx` to handle the delay logic before starting the progress bar.
* Add documentation for the new `delay` prop in the API section of `README.md`.
* Add tests in `src/__tests__/HolyLoader.test.ts` to verify the functionality of the `delay` prop.