[css-overflow-5][editorial] use the right attribute

Author: tabatkins

css-overflow-5/Overview.bs

@@ -381,7 +381,7 @@ The four ''::scroll-button()'' pseudo-elements are individually selected
 by the selector's argument.
 The possible <dfn><<scroll-button-direction>></dfn> values are:
 
-<dl dfn-type=value for="<scroll-button-direction>, ::scroll-button()">
+<dl dfn-type=value dfn-for="<scroll-button-direction>, ::scroll-button()">
 	: <dfn>up</dfn>
 	: <dfn>down</dfn>
 	: <dfn>left</dfn>