In this change set I am changing the guidance in the README
and in comments to put the class on the correct tag: `<code>`, not `<pre>`.
If you put the `hljs` class on `<pre>`, syntax highlighting
does not use the correct padding.
You can see from the default CSS stylesheet in the highlight.js
repo that the `hljs` tag is expected to be on the `<code>` tag:
84719c17a5/src/styles/default.css (L17-L25)
All the official highlight.js examples have the `hljs` class on `<code>`:
https://highlightjs.org/static/demo/