Install Warning

[esnible]

Running npm install now produces a scary message:

 Verion 9 of Highlight.js has reached EOL.  It will no longer
  be supported or receive security updates in the future.
  Please upgrade to version 10 or encourage your indirect
  dependencies to do so.

  For more info:
  
  https://github.com/highlightjs/highlight.js/issues/2877
  https://github.com/highlightjs/highlight.js/blob/master/VERSION_10_UPGRADE.md

[Sodman]

We should definitely fix this, but it's worth noting that this is currently only used by typedoc, which is only used for docs generation. It's not used as part of the runtime itself.