@cr1901 @b0rk @simontatham for certain tools that have a capital-M Manual—you know, the organized kind that you'd get an HTML or PDF render of—you'll sometimes find the HTML packaged in Linux distros (as a separate -doc subpackage if not in the main package itself). but to open such docs, you'll have to root around in /usr/share{,doc}, and that's if you know the manual exists in the first place; you might just as well find a bare-minimum README...
seems like there's an unfilled niche for making a system's heterogenous doc tree more discoverable. something with slightly more tailored UI than a directory tree view (let alone navigating to each one individually). a generated HTML page would be a good start, and a plugin for KHelpCenter and such would be really cool. it's entirely possible there's an existing solution here I'm just not familiar with, though