As discussed here: https://support.zendesk.com/hc/en-us/community/posts/222554808-Help-Center-Formatting?page=1#community_comment_115005136628

You're using a stripped down TinyMCE editor which I like. TinyMCE has a new excellent official code sample plugin.

You can try this out on their full featured demo

The menu item looks like this:

Give it a try - it's excellent and it offers syntax highlighting via prism.js

It would be a relatively small amount of developer time to implement this on Zendesk Help Center and would be a huge win for Zendesk customers writing articles with code samples.