[css-transitions-2] Move composite order section to better reflect level 1 spec outline

Author: birtles

css-transitions-2/Overview.bs

@@ -111,6 +111,8 @@ Issue: Define the above more precisely once we rewrite firing of transitions
 in terms of Web Animations concepts (specifically when we spell out when we
 cancel an animation).
 
+# Application of transitions # {#application}
+
 ## Animation composite order ## {#animation-composite-order}
 
 <a spec='web-animations'>Animations</a> generated from the markup defined in