Scrollspy and HighlightJs not playing nicely together

[SinisterMinister]

If you have a document of substantial length with a lot of code blocks, Scrollspy will fall out of sync as HighlightJS does its stuff after Scrollspy has been applied.

For an example, I clicked on the .tugboat/app.json link in the sidenav, and you can see that it's not correctly lining up the content with the navigation.

The fix is simple and I'll attach a PR with it.