Update the image link for the Images examples

[thomkiraly]

All Images examples (Chapbook, Harlowe, Sugarcube, and Snowman) currently use https://twinery.org/homepage/img/logo.svg for their examples. This results in no image being displayed/page not found.

One correct image URL as of Oct 26 2024 is https://twinery.org/icons/twine.svg

This pertains to both the downloadable and twee code examples.