Would it be possible to put the empty talk page image on Commons? I'd like to add it to w:Help:Introduction to talk pages/1.
Topic on Talk:Talk pages project/New topic/Flow
Yes, this is possible. I'm pretty sure that @JKlein (WMF) is planning to do this.
Since the tool is not widely used at the English Wikipedia, this might be a little early to update the documentation. Also, would a screenshot of the whole page make more sense?
I want to add it more as a decorative element than an instructional image, similar to here (I don't think w:MOS:PERTINENCE really applies to the help tutorial).