sRGB definition re-check
See:
- https://photosauce.net/blog/post/making-a-minimal-srgb-icc-profile-part-3-choose-your-colors-carefully
- https://photosauce.net/blog/post/what-makes-srgb-a-special-color-space
and if we happen to have written down the bad values from the sRGB draft rather than the non-free accepted spec, at least delete them.
Re-evaluate what we want to say about sRGB and which definition and values to use.
Thanks to @JonnyMako for mentioning these posts in wayland/wayland-protocols!14 (comment 1196966) .