[css-ruby-1] Add property name to section title.

Author: fantasai

css-ruby-1/Overview.bs

@@ -1199,7 +1199,7 @@ Ruby Text Decoration</h3>
 Edge Effects</h2>
 
 <h3 id="ruby-overhang">
-Overhanging Ruby</h3>
+Overhanging Ruby: the 'ruby-overhang' property</h3>
 
 	<pre class="propdef">
 	Name: ruby-overhang