updated header of overview section

Author: jpeng-ms

articles/communication-services/concepts/ui-library/includes/mobile-ui-library.md

@@ -13,7 +13,7 @@ ms.custom: kr2b-contr-experiment
 
 *Composites* are turn-key solutions that implement common communication scenarios. You can add video calling experiences to your applications. Composites are open-source higher-order components that developers can take advantage of to reduce development time and engineering complexity.
 
-## Composites Overview
+## Composites overview
 
 | Composite | Use Cases |
 | :-------- | :-------- |