Rephrase Step 4.4 to eject from the sidebar in Finder
During #18784 (closed), both P1 and P4 tried to eject the disk image of balenaEtcher from the desktop, as currently instructed, but couldn't find it there.
The note about this step being optional helped, but they were still a bit unsure.
Instead we should instruct to eject it from the sidebar of Finder, which is more at hand and probably more reliable.