Add troubleshooting info about marker scaling differences between operating systems.

[TimMonko]

We need to add the marker scaling issue to the Troubleshooting page, it has popped up again (see vispy/vispy#2078) for a user. This doesn't help solve the problem, but it at least makes it more findable, hopefully.

Just for the record:
Here's the root issue, in vispy:
vispy/vispy#2078
napari issue, was closed in favor of the vispy one:
napari/napari#2894

What I think we should do is add this to the trouble shooting page:
https://napari.org/stable/troubleshooting.html

Originally posted by @psobolewskiPhD in #8050

[kesterlester]

Another helpful suggestion from someone else was that a runtime issue be perhaps printed. See suggestion here: vispy/vispy#2078 (comment) . I suspect this suggestion may have helped me more than the troubleshooting page, as I didn't really know I had a problem (and so wasn't looking for solutions) until after I'd already done lots of development. In contrast, a runtime warning (like the ones that say "feature X is now deprecated and may be removed in version Y ..." are very visible to developers (and helpful, in my opinion) -- and so may have alerted me to a potential issue earlier.

Of course, that is not an argument against also having things on the troubleshooting page.

[alisterburt]

+1 on a runtime warning!

Potentially quite loud so probably best done on layer construction

Apologies if I came off rude @kesterlester - I was having a bad day