Best practices issues

[dustinwhisman]

Not all issues will neatly map to WCAG guidelines, and there may be more info-level issues we want to highlight based on bad HTML practices, like divitis. This can be the dumping ground for these types of issues.

Includes

• Configuring the extension to allow users to toggle issues for best practices on/off
• Writing CSS and/or JS to highlight issues related to best practices (at least one issue, we can expand on this later)
• Ensuring that info/error/warning messages make it clear that these are recommendations, not WCAG requirements