This has been discussed on page 3: Github uses pygments 1.3, which does not support AHK. I sent a request to github support, they told me they'll upgrade, which they apparently haven't done yet.
I found it, thank you, sorry for not having searched before asking . . .
It's a known issue. For some reason Pygments won't render AutoHotkey code on GitHub-Pages. We've been discussing it on and off for the past few pages.
And that's exciting, I will learn a lot from the book AND the forum . . .
I can stand waiting for the issue to be fixed.
Thanks for that ebook.