Stopping the "New Microsoft Edge" Nag (Firefox)

I did suffer through the “introduction” session, and I unpinned Edge from my taskbar. What I’m talking about is this, which shows up on the bottom of the screen you’ll have to click it to see the actual image):
Imgur
Sorry about the skewed image — it’s not that big — but for some reason an embedded link doesn’t want to work.

I should note that it seems to be occurring less and less, so it may be that Windows is getting the message that I’m not interested. If that be the case, then this discussion is kind of moot except from a curiosity perspective.