They refer you to the linux docs, because there are lots of different Linux distributions out there. Obviously, they can't cover them all.
Funny that you laugh about the "linux boot manager" instead of how it says linux system can be installed on the swap partition. Obviously the details are incorrect and it's stating irrelevant stuff, but so what?
Also, ctrl+alt+del reboots in many linux systems, or at least it used to do so back in the old days. It was configurable, and I remember I used to have it bound to "shutdown -r now"
The documentation probably serves those who need it just fine. It's not written for you. Use the feedback box at bottom of that page to tell them how you'd correct and/or improve the descriptions. Go ahead.