README: "learn about shaders and CYOS" link dead

[khelkun]

The link on the README is https://www.eternalcoding.com/?p=113 but leads to the home page of the blog.

I guess the original blog post was this one: https://www.eternalcoding.com/what-do-you-mean-by-shaders-learn-how-to-create-shaders-with-babylon-js/

Still the image links on this blog post are dead.

[sebavan]

cc @deltakosh