Add TypeScript definitions

[ronami]

Summary

Hey, pretty straight-forward: Adding some TypeScript definitions.

[sindresorhus]

Thanks for creating a TypeScript definition. 🙌 Can you follow this styleguide?

Some examples:

• https://github.com/sindresorhus/semver-regex/commit/039944bb5b3876913171b895488874b5c200e458
• https://github.com/sindresorhus/global-dirs/commit/0aae4d64887f77af94c4fb7ca12aa9f93c0a8291
• https://github.com/sindresorhus/md5-hex/commit/bbbfeff840f26973fbffc16d4863ae6d120079f3

[ronami]

Hey, I updated the PR by documenting the types in index.d.ts.

Just pointing out some things in the PR:

• I used any over unknown to match Node's definition: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/node/globals.d.ts#L192.
• I used the example from the README.md which uses 2 separate files. I wasn't sure how to document it so I used two sets of ```s.

I went over the styleguide and didn't find anything that's missing, is there anything specific I should fix?

Thanks!

[sindresorhus]

I used any over unknown to match Node's definition: DefinitelyTyped/DefinitelyTyped:types/node/globals.d.ts@master#L192 .

The Node.js type definitions are not very good nor strict.

[sindresorhus]

Looks good. Thanks :)