[CSS21] Feedback hyperlink: append subject

Regarding the section Cascading Style Sheets Level 2
<http://www.w3.org/TR/CSS2/cover.html>  Revision 1 (CSS 2.1) Specification,
Status of this document:

Replace:

The (archived <http://lists.w3.org/Archives/Public/www-style/> ) public
mailing list www-style@w3.org (see instructions
<http://www.w3.org/Mail/Request> ) is preferred for discussion of this
specification. When sending e-mail, please put the text "[CSS21]" in the
subject, preferably like this: "[CSS21] .summary of comment."

With:

The (archived <http://lists.w3.org/Archives/Public/www-style/> ) public
mailing list www-style@w3.org
<mailto:www-style@w3.org?subject=%5bCSS21%5d%20.summary%20of%20comment.>
(see instructions <http://www.w3.org/Mail/Request> ) is preferred for
discussion of this specification. When sending e-mail, please put the text
"[CSS21]" in the subject, preferably like this: "[CSS21] .summary of
comment."

(The change is in the mailto URL, so it is probably invisible in plain text)