Currently Krita manual is only available through docs.krita.org. It is inconvenient in case there is no internet connection, and requiring it is not a good UX. If I'm not mistaken, Krita is advertised as full-offline-capable software, and without help content this claim, in my opinion, is not met. At least a snapshot before the release should be bundled with Krita, and it should be displayed instead if there is no connection. Ideally, the help content should be available through the Krita interface, without the need to open a browser. The standard KDE help window should be used.
I'm sorry but we cannot possibly bundle the manual in all languages with Krita, that would make the download extremely big. If the user needs the manual offline they can download the manual in epub from https://docs.krita.org/en/index.html, specifically for english from here https://docs.krita.org/en/epub/KritaManual.epub