Modern documentation supports both Engineering and Marketing/Sales.
Modern documentation focuses on presenting the all aspects of your product in a meaningful, usable manner.
To be meaningful, documentation targets your product's functionality and capabilities. Although it presents your product in the best possible light, meaningful documentation does not include marketing hyperbole.
To be usable, documentation speaks to readers at their level of understanding. Although it describes your product thoroughly, usable documentation does not include unexplained technical terms.