delete porting issue

Author: svgeesus

css-fonts-4/Overview.bs

@@ -2889,8 +2889,6 @@ Individual values have the following meanings:
 
   </dl>
 
-Issue: Moved to Level 4; port the text for this from Fonts 3 .src to Fonts 4 .bs
-
 <h3 id="font-feature-values">
 Defining font specific alternates: the ''@font-feature-values'' rule</h3>