Fix typo

Author: mirisuzanne

css-cascade-5/Overview.bs

@@ -1158,7 +1158,7 @@ Layer Identifiers</h5>
 
 	Layer identifiers do not cross the shadow DOM boundary,
 	so the ordering of layers in the light DOM has no impact
-	on the layer of identically-named layers in the shadow DOM.
+	on the order of identically-named layers in the shadow DOM.
 
 	Issue(w3c/csswg-drafts#4984): How do Cascade Layers interact with Shadow DOM?