Added hello world line to DemoApplication

src/main/java/com/example/demo/DemoApplication.java

@@ -9,7 +9,7 @@ public class DemoApplication {
 	public static void main(String[] args) {
 		SpringApplication.run(DemoApplication.class, args);
 		System.out.println(new Date());
-
+		System.out.println("Hello World!");
 	}
 
 }