[css-borders-4] Added Oriol Brufau to acknowledgements (w3c#9127)

Author: SebastianZ

css-borders-4/Overview.bs

@@ -786,5 +786,6 @@ Additions since [[CSS3BG]]</h3>
 	and [[CSS3BG]] predecessors to this module,
 	the editors would like to thank
 	Tab Atkins,
-	and Håkon Wium Lie
+	Håkon Wium Lie,
+	and Oriol Brufau
 	for their suggestions and feedback specifically for this Level 4.