Screenshots and screencasts refers to "Take a Screenshot" in the overview
The Screenshots and screencasts page suggests two ways to take a screenshot:
Press the Print key or launch Take a Screenshot from the Activities overview.
I think "Take a Screenshot" here is referring to the shortcut that appears if one searches for "screenshot" using desktop search, but this is an obscure feature and this paragraph doesn't provide enough information for someone to find it if they aren't aware of it. Instead, it is more like that a user will hunt through the apps grid and not find it.
Instead, I'd suggest something like the following, borrowing from Log out, power off or switch users:
Press the Print key, or click the system menu on the right side side of the top bar and click the Screenshot button.