Problem with importing a separate hash module in Typescript

According to docs one can import a separate hash module like this:
```ts
import sha from `hash.js/lib/hash/sha/512`;
```
But in this case Typescript emits the following error:
```
TS2307: Cannot find module 'hash.js/lib/hash/sha/512'
```
This can be fixed by creating a type definition file in user-land with the following contents:
```ts
// hashjs.d.ts
declare module 'hash.js/lib/hash/sha/1' {
import {sha1} from 'hash.js';
export = sha1;
}
```
But it would be awesome to support such imports out of the box.

Start by reproducing the TypeScript error for the documented import of hash.js/lib/hash/sha/512 and review the example hashjs.d.ts declaration. The work is done when the separate hash module resolves without a user-land declaration file.

Written by the indexing model from the issue text.