Let's be more targeted then: Instead of a general comment on backends, add the following below the plot code:

If no plot shows up, please check [Toubleshooting].

which may link to https://matplotlib.org/devdocs/faq/troubleshooting_faq.html and should get a section on "my plot does show".

That's probably worth a second PR, because a really helpful guide to "it doesn't work" needs some care.

Originally posted by @timhoffm in #21335 (comment)