I'm not sure, because this is not always needed, you can very well snap a window to an edge too...
I see. Maybe to mention two possibilities that currently exists?
One possibility is to select and edge of the Wall (usually for inserting doors) and second possibility to enable passive snap mode when using a Wall Face (usually for inserting window)?
The problem is if this will not be mentioned a lot of (new) users will not be able to successfully insert preset window in the wall when following the instructions.
I think the text is correct in the tutorial? It says not to select anything...
How to use
Using a preset
If you are going to draw your window directly on a wall, select one face of a wall
Press the Arch Window.png Arch Window button, or press W then I keys
Select one of the presets in the list
Fill out the desired parameters
Creating from scratch
If you are going to draw your window directly on a wall, select one face of a wall
Press the Arch Window.png Arch Window button, or press W then I keys
A new sketch will be created (on the selected wall face if applicable). Draw one or more closed wires
Press the CLose button in the task panel to create the window
Enter Edit mode by double-clicking the window in the tree view, to adjust the window components
Using a preset instructions suggests first thing to do is to select one face of a wall? By doing that clicking on Arch Window tool (step 2) will enable "sketch mode" and not offer dialogue where user can select one of the presets available. Instructions under step 1 should say something like "Deselect any previously selected face/edge on the wall prior pressing Arch Window tool button."?
