[css-ui-4] Update change section

Author: frivoal

css-ui-4/Overview.bs

@@ -2668,6 +2668,7 @@ This appendix is <em>informative</em>.
 
 <ul>
 	<li>Added details about form control specific rendering rules
+	<li>Clarify interaction between text-overflow and annonymous block containers
 </ul>
 
 <h3 id=changes-22-09-2015 class=no-num>Changes from the