Update print related comments in `main.css` file

Use correct terminology and remove the outdated parts of the comments.

See also:

 * JavaScript URIs:
   https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/void#JavaScript_URIs
 * URL fragments:
   http://www.whatwg.org/specs/web-apps/current-work/multipage/history.html#scroll-to-fragid
 * `href` attribute:
   http://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#attr-link-href
   https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#attr-href