Add missing comma to light-mode selector example

[charliermarsh]

Summary

The dark-mode example (a few lines below) has a comma here, but the light-mode example does not. I think it's just missing, since IIUC this should be an "OR" query.

Thanks for the great project! (We use mkdocs-material to power the Ruff documentation.)

[squidfunk]

Thanks for the PR! Jup, there needs to be a comma. Good catch! Oh, and I'm psyched to see Ruff use Material for MkDocs!

[charliermarsh]

Of course!

I will admit that I didn't look into it deeply, but I also had to add this (I believe only the latter was necessary -- dark-mode-only images still had display: none in dark mode):

[data-md-color-scheme="astral-light"] img[src$="#only-light"],
[data-md-color-scheme="astral-light"] img[src$="#gh-light-mode-only"] {
  display: inline; /* Show light images in light mode */
}

[data-md-color-scheme="astral-dark"] img[src$="#only-dark"],
[data-md-color-scheme="astral-dark"] img[src$="#gh-dark-mode-only"] {
  display: inline; /* Show dark images in dark mode */
}