The page that describes the formatting of the posts: https://sharepoint.stackexchange.com/help/formatting contains the dead link for Google Prettify.
The dead link is: http://google-code-prettify.googlecode.com/svn/trunk/README.html
Since google prettify has moved to Github, the new link should be:
https://github.com/google/code-prettify/blob/master/README.md