User manuals across different Teams –document management solutions?

IT team produced general user manuals how to do various tasks in the system 1 year ago and store them on SharePoint. Now it became obvious that teams across business have their own guides, more of a business process than general ones and all new documentation is stored only within their own department. The problem we have is what would be the best way to manage user documentation? It is clear that manuals are spread and modified across teams and kept in word docs not shared with other teams. Does it make sense for IT department to create one all inclusive guide accessible to all within the business? What would be the best way so that the guides are user friendly and easy to find information? Currently every separate task of the system is documented in separated word doc stored in folders depending on the topic. Would web-page based guides be a way forward or there are other solutions?