Ask HN: What tool do you use for creating technical documentation?

I want to create JavaScript and Python SDK documentation to share with (enterprise) clients in portable format likes PDF etc. Solutions like readme.io and readthedocs.io are good only for a web-based approach.

Sadly, Google Docs isn't a great option here even after using add-ons like Code Format and Prettier.

Let me know if I've missed something which is already around.