this is just an idea of what I have found extremely useful when I had to deal with the web-based continuous integration system Hudson (Jenkins, these days) in the past:
They have all the pieces of information that you usually have in a manual in every page, exactly where you are interested in it.
In most cases the information is hidden and clicking the round help button toggle between the information being visible or hidden.
I took some simple screenshots of this:
Another good point about this approach is that you see what is not documented while using the software. If you have a separate manual careful list keeping and manually matching what is in the user interface and what is in the manual must be done.
Kind regards
Clemens Anhuth