Add a script that generates the .d.ts files based on current documentation

[NuriYuri]

Supposedly fixes #340

I've noticed that openapi-generator-cli was making a file with class names that do not match some of the exported classes. The documentation in the other hand is quite accurate, it just have few issues like inconstant case style.

With that in mind I decided to write a tiny script that converts the documentation to a .d.ts file. I think it's a decent alternative while waiting for actual typescript definition or bigger fixes in the code to have classes that matches the open-api docs :)