[css-animations-2] Update heading syntax

Author: birtles

css-animations-2/Overview.bs

@@ -200,11 +200,11 @@ it must be set to true.
 
 </div>
 
-<h2 id="events">Animation Events</h2>
+# Animation Events # {#events}
 
-<h3 id="event-animationevent">Types of <code>AnimationEvent</code></h3>
+## Types of <code>AnimationEvent</code> ## {#event-animationevent}
 
-	<p>The <em>additional</em> types of animation events that can occur are:</p>
+The <em>additional</em> types of animation events that can occur are:
 
 	<dl dfn-type=event dfn-for=animationevent>
 		<dt><dfn>animationcancel</dfn>