Knowledge Management in the context of software user documentation implies making use of multiple opportunities for your users to access extra information and used to build tacit knowledge. This information is usually outside the direct use of the software but directly related to business processes within which the software operates.

• Information such as further reading of procedural and policy documents (Reading Aids), answers to Frequently Asked Questions (FAQs), encyclopaedic information (Wikis) relevant to the business and operations and also the accumulation of knowledge gathered within a help-desk support environment.
  
  
• Depending on the nature of the software, there are times that business complexity such as operational processes and policies when using the software is beyond the confines of the user documentation and consequently requires consideration outside of the software. 
  
  
• It makes sense then, to associate the user documentation to an information architecture of knowledge management, usually located in a Knowledge-base or Document Management repository available to all users of the software. This information could also be made available to shareholders, employees and even customers.
  
  
• At the same time, it is self-evident that any modern business should have all its information and knowledge in an easily accessible form, such as a Knowledge-base and a Document Management System for online access by users, shareholders, employees, suppliers, and customers. No more paper, no more classrooms.

Reference: Wikipedia Knowledge-base (Wikis, Forums, FAQs)
Reference: Wikipedia Document Management System (DMS)