[author] highlight.js 7.5 and 8.0

Updating highlight.js  with two most recent versions.

- The directory structure changed (i.e., "lang" renamed to "languages") as it is the one our CDN build actually uses, the previous was wrong.

- Sorry for placing two commits in the pull-request. I messed it up locally and noticed only after pushing the first part, didn't know how to edit an already published commit. Hope it's okay.