[css-contain-1] Markup fix

Author: xfq

css-contain-1/Overview.bs

@@ -70,7 +70,7 @@ Strong Containment: the 'contain' property</h2>
 	<wpt>
 	contain-animation-001.html
 	inheritance.html
-	</wpt
+	</wpt>
 
 	<p class=all-media>User Agents are expected to support this property on all media, including non-visual ones.</p>