You can use the one-page template as complete documentation for your products. A slider on the top will denote the amount you have studied on the page. A progress overlay on the left column also represents the progress of one topic.
You can press CTRL+F to search within the document. It will act as the browser does. An instant searching experience. Overall, this is a proper solution if you document is not scattered around multiple pages.
CTRL+F
Spider-themes 
Helpdesk 
EazyDocs 
BBP Core Demo 
