[css-text-4] Fix markup error

Author: frivoal

css-text-4/Overview.bs

@@ -35,7 +35,7 @@ Introduction</h2>
 <h2 id="transforming">
 Transforming Text</h2>
 
-<h3 id="text-transform-property" oldids="text-transform caps-prop">
+<h3 id="text-transform-property" oldids="text-transform, caps-prop">
 Case Transforms: the 'text-transform' property</h3>
 
 	Issue: Add final level 3 content