[css-borders-4][editorial] Removed the issue about multiple border colors (#9593)

Author: SebastianZ

css-borders-4/Overview.bs

@@ -95,9 +95,6 @@ Introduction</h2>
 		<img src="images/multicolor-border-dotted.png" alt="">
 	</div>
 
-	Issue: The syntax for comma-separated multiple colors
-	<a href="https://github.com/w3c/csswg-drafts/issues/1172#issuecomment-379878579">is still under active discussion</a> in the CSS WG.
-
 <h2 id="corners">
 Corners</h2>