b2evolution can manage interactive online manuals just like the one you are looking at right now.

Main features:

• Similar to a Wiki but with added hierarchical structure
• Unlimited nesting of Chapters & Sub-chapters
• Easy linking between pages via WikiLink syntax – links stay valid even if you restructure the table of contents differently or if you rename the pages
• Collaborative editing, including versioning of edits, history, diffs and rollback.
• Multiple markup options making editing easier and more consistent than HTML editing
• No frames, so each page has an URL and it’s easy to share links to individual pages
• Allows user comments
• Allows user rating of manual pages
• and of course all the other b2evolution standard features (Analytics, Antispam, etc.)