Include reference to JPEG XL in "Tips for Sustainable Websites"

[sbutler-gh]

From: https://sas-dhrh.github.io/dhcc-toolkit/toolkit/minimal-computing.html#tips

Minimal web design for absolute beginners

Use the newer WebP image format (but keep your eye on browser compatibility).

Like WebP, jpegxl is an image format in the works that I understand is making even bigger strides in implementation. The community behind jpegxl is pushing for its adoption and integration into browsers like Chrome, Firefox, Brave, etc, which is the way it would become usable for everyday people — and start making a significant reduction in the file size and footprint of images. Controversially, Google recently decided not to include jpegxl in a new Chrome update (a decision which may have had to do with Google trying to get more support for a compressed image format they built themselves, .avif)

So I'm not sure if there's anything concrete for JPEG_XL yet, but perhaps it could be a placeholder (e.g. "And look out for JPEGXL when it becomes available in your browser, and ask the people making your browser to incorporate it too! <--- with a link to a request form to Chrome devs, Firefox devs, Brave devs, etc)