[Zeek] Bro/Zeek Script Support in Highlight.js

[Foster McLane]

Hello all!

I've put together a language file for the popular Highlight.js library for the Bro/Zeek script language. Highlight.js is the syntax highlighting library Discord and Slack use and is useful for websites that include automatic client-side syntax highlighting.

Let me know if you have any comments or suggestions! If you don't, a thumbs-up on the pull request would be appreciated to gauge how much people want this feature in Highlight.js.

GitHub PR Link: https://github.com/highlightjs/highlight.js/pull/1997

Thanks!

Foster