Is your feature request related to a problem? Please describe.
Typescript developers rely on type definitions for their IDEs to provide reliable autocompletes. This gives them the ability to discover the API of any given library a lot faster than by referring to documentation. nlp.js would be more accessible and find more adoption and be overall even more awesome than it already is.

Describe the solution you'd like
Provide type definitions via Definitely Typed.

Describe alternatives you've considered
Alternatives could be:

1. An API documentation could be provided.
2. Types could be added to the code. As typescript is a superset of javascript it could be done iteratively. This enhances the maintainability of the code as it allows for IDEs to help with refactoring. The code would have to be transpiled to javascript which would in turn generate the code as it is now or something very much similar.

Additional context
https://github.com/DefinitelyTyped/DefinitelyTyped (31k Github Stars)
http://earlbarr.com/publications/typestudy.pdf (Bugs can be found using Typescript)
https://madnight.github.io/githut/#/pull_requests/2020/3 (7.5% of all repositories are Typescript. 20.17% of all repositories are Javascript)
https://www.typescriptlang.org/ (Typescript website)