Hello @Nicolas_Zullo and welcome to the forum ,
We have sections within projects that contain documentation and notes. In addition, we keep curated spaces in Asana for one on one meetings as well as staff meetings. The notes taken in those meetings live in those spaces as well. We feel that it’s easier to find notes pertaining to those times and projects if they live in the same space. Asana has great training modules if you haven’t already checked them out in the Asana Academy (https://academy.asana.com/). Check out the Meeting Agendas module in the Academy and the Meeting Agendas, One on One, and Brainstorming guides below to get you started thinking about how you might want to organize that type of information in the Asana space.
In general we try to minimize how many project spaces we have to keep track of so we typically just put all of the information within those sections rather than creating general Notes, Brainstorming, etc spaces. If you are working within a team and want to have those types of spaces I would lean towards having those private so it doesn’t clutter up the shared space.