[css-fonts-4] remove scary warning about immaturity

Author: svgeesus

css-fonts-4/Overview.bs

@@ -27,11 +27,6 @@ spec:css-fonts-3;
 		text:font-kerning
 </pre>
 
-Advisement: This document contains ideas and
-experiments that might or might not end up in the final version of a CSS
-Fonts specification. Implementors are encouraged to ask about the status
-of a particular feature listed here on the <code>www-style</code>
-mailing list.
 
 <h2 id="introduction">
 Introduction</h2>