Disable autolink in example code blocks in guides.

/cc @chancancode @robin850

configuration reference: http://alexgorbatchev.com/SyntaxHighlighter/manual/configuration/

Related issues:

* https://github.com/vmg/redcarpet/issues/334

* https://github.com/docrails-tw/guides/issues/62
Merge pull request #15886 from JuanitoFatas/disable-autolink

Disable autolink in example code blocks in guides. [ci skip]