Add body class when loaded - fix #8

[stefanjudis]

I was just about to implement the polyfill and came across #8. It addresses my concerns completely because the CSS I have in my project is as follows. 👇

  :focus {
    outline-style: dashed;

    &:not(.focus-ring) {
      outline: none;
    }
  }

This can destroy the complete focus handling in case of JS failure or loading troubles.

This PR adds the discussed behavior of the polyfill to add a focus-ring-enabled class to the body element when it's done doing its magic. ;)

[stefanjudis]

Marked as non substantive for IPR from ash-nazg.

[stefanjudis]

These JSDOC changes are not intended by me. It seems like the docs in the dist file were not up to date. Now they're matching with the docs in src.

[robdodson]

LGTM thank you @stefanjudis!

[stefanjudis]

Thanks so much for merging.

Do you plan to also release a new version? 😊

[robdodson]

Yep I just want to check in with @alice first