"Download openSUSE Leap 42.1" and "Download openSUSE 42.2 Beta 2":
 - Section "Need help?":

"User manuals are available from activedoc.opensuse.org" points correctly to
the "Documentation" page.
 - Despite the possible error of <http://activedoc.opensuse.org/> instead of
<https://doc.opensuse.org/>

But, "for example the Official Start-Up Guide." (URL =
<http://activedoc.opensuse.org/book/opensuse-start-up/>) also lands at the
"Documentation" page.

I suspect that, the correct URL for the "Official Start-Up Guide" would be
<https://doc.opensuse.org/documentation/leap/startup/html/book.opensuse.startup/index.html>.