Hi @SebasMorales,
In my experience, writing documentation for Power Apps is mainly manual work.
We manually create
(1) ERD / UML diagrams for our database
(2) Write functional documentation
(3) Write technical documentation by going over each screen with a screenshot and discussing the most important features.
(4) (technical documentation for any flows running in the back-end)
However, I have heard of some way to speed up the creation of your app documentation. With XRM ToolBox you have tools that allow you to automatically generate the relationship diagram of your database (for Dataverse). I recently also saw a way to auto-generate documentation on your technical app components. I don't know all the details or limitations but this video gives a comprehensive overview of the capabilities .
As a closing note: one of the great advantages of Power Apps is that the components and the Power App Editor are very visual. This means that the actual 'need' for in-depth code documentation is lower.
If the components within your app or solution (variables, collections, controls, flows...) are properly named, the code is well formatted and well commented, you won't have to look at the code documentation at all. That being said, documentation about the app,the database and table relations (especially the latter 2) are always very appreciated by developers. 😉
If this solves your question, would you be so kind as to mark it as a solution.
This allows other users with similar issues to find it more easily.