[css-flexbox] typo

Author: tabatkins

css-flexbox/Overview.bs

@@ -878,7 +878,7 @@ Implied Minimum Size of Flex Items</h3>
 	New computed value: the percentage as specified or the absolute length or a keyword
 	</pre>
 
-	<dl dfn-type=value dfn-for="min-width, min-height">
+	<dl dfn-type=value dfn-for="min-width min-height">
 		<dt><dfn>auto</dfn>
 		<dd>
 			On a <a>flex item</a> whose 'overflow' is ''overflow/visible'',