Document management without project

You can just create a Product.
A document must be linked either to a project or to a product.

Your remark pointed an issue :
- users with visibiilty not extended to "all project" cannot see documents not linked to a project.

=> This will be fixed in next version : anyone allowed to access docs should be able to see docs not linked to a project.

=> Workaround :
1) set right as manager+ to all profiles who should access non project docs
2) create a specific "doc" project", affect users to this project and set project of docs as this project.