Add section to highlight what was evaluated

[mgifford]

The OpenACR should highlight what does this report represent. Is it a random sampling? Is it following WCAG-EM's approach. Did they follow critical user paths and evaluate all the pages along the way? Was the site crawled using an automated tool?

Essentially the explore step here https://wcag-em-report-tool-2021-redesign.netlify.app/evaluation/explore-website