Like I said with all due respect whoever wrote that should've at least at the minimum done a Google Search. That's also not an Apple Site. If it was, it would be https://, not http://. Right there it should be noted that it's external. Which means Apple didn't write the document. Someone else that doesn't work for Apple did. An official guide/instruction manual however does exist, and can be found on iBooks, if you do a basic search. That's official. I have one for my 6S Plus that I downloaded.
Your part on "education" does not apply because of the above.
In short, that site is not official. I'm using Firefox on my laptop. On my address bar, it says "Apple Inc. (US), with a green padlock and the page that I'm on right now. This is official. On that site that you gave, this is absent.
Double check this for yourself.
With all due respect.