What is the best way for documents- user guides UI (easy navigation, sharing between teams)?

We (IT team) store general user manual about software system as word doc in folders on SharePoint. Other teams across business adopted the guides to their own business processes and store them only within their own departments. What would be the best way to manage user documentation? 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?