Hi,
So I did some digging, and adobe acrobat and some online services allow you to convert simple websites to pdf. I tried, and they don’t work on the user guide.
If you only need some pages offline, you can always print individual web pages as a PDF from your browser, and then use Adobe Acrobat or something like SumatraPDF to assemble the pages into a single document. You won’t have the links between the pages, but all the info will be there.