Documentation should always have some built-in capability to receive comments and the comments should generate alerts to the content owners.
This process can vary greatly. In some contexts, readers can be allowed to edit the content. Or only some users. Those edits should still trigger alerts to the content owners for review.
Documentation often becomes stale because there is no easy way to communicate changes. Capturing improvements or updates at the time the document is used is the next best thing from when the content needs revision because what it describes has changed.
Bonus approach
For software documentation (especially for enterprise applications), if you use any kind of ticketing or kanban-style stories, include “Create/Revise Documentation” as a standard part of the Acceptance Criteria in your template.
© Scott S. Nelson