[css-ui-4] Update changelog

Author: frivoal

css-ui-4/Overview.bs

@@ -2643,6 +2643,12 @@ Changes from the <a href="https://www.w3.org/TR/2021/WD-css-ui-4-20210316/">16 M
 
 		<li>
 			Added <<image-1D>> as value for the 'outline-color' property.
+
+		<li>
+			Retired the <code>invert</code> value of 'outline-color'.
+
+		<li>
+			Added the ''outline-color/auto'' value of 'outline-color'.
 	</ul>