Just download it to your ipad and pick "open in Ibooks" or download it to your computer and email it to yourself and then pick "open in iBooks" from your iPad.
The "un-named" entry at the top is the table of contents as in the help file and it scrolls on my iPad. However it does block the screen content. If you choose to scroll the "table of contents" from Ibooks it is not hierarchically organized - but the screen is full. Best way to find something after that is to do a search. Its very comprehensive. (My continuing love/hate relationship with technology.)
Its a spectacular resource on an iPad Pro. If you have an android tablet, go to Google Play and search for "epub reader".
