Investigate if <details>/<summary> is a good choice for our Checklist

[ericwbailey]

We currently use the details and summary elements for our Checklist page. These element allow for a native expand/collapse experience, without the use of JavaScript.

Our checklist items do not use heading elements, which was a concern voiced in this thread on the web-a11y Slack. There is also mention of concerns around interactive content placed within the summary element, which we do use for both WCAG links and permalinks.

Additionally, this repo by Melanie Sumner highlights other potential issues.

We should revisit our usage of details and summary elements to see if they are usable, or if an ARIA construct would be a more desirable replacement.