Over the years every time I've upgraded my Ubuntu installation or moved up to the next LTS I've found that for some reason many help manuals are not installed.
For example I'm trying to choose the position of the Compose key, in the Keyboard Layout Options, in the Keyboard Preferences Mate application. Now I have some questions about some of the choices offered like what the <Less/Greater> key is. So I click on the bottom left "?Help" button and a window opens up to tell me the help is not installed. Now even if the answer is not in that document, there will be some answers for possible future question, and it seems like a logical first place to look.
I've looked and I can't find how to install these manuals. Of course there are the CLI manuals but they tend to be very brief.
How to get a list of available manuals and how do you install them so that when you click "?help" they work ? Thanks.