Plasma/FAQ is a redirect which always points to the latest version, so it's best not to use the link with the version number.
Sure. So, what to do if user is on 4.4 (4.3, 4.5 soon (hey, Plasma developers, where are you?), etc.) and wants to be instructed how to add a widget on his panel? ;)
On every Plasma/FAQ/whatever page there is an info box directing to the earlier versions :-)
Yes, really. 4.4 says For older versions you can turn to the KDE 4.3 specific page, theKDE 4.2 specific page, the KDE 4.1 specific page or the KDE 4.0 one
4.3 says For older versions you can turn to the KDE 4.2 specific page, KDE 4.1 specific page or the KDE 4.0 one
and so on. And they are all links.