Added design mockup

Author: phpcontrols

README.md

@@ -4,4 +4,6 @@ Built on [phpGrid Enterprise](http://phpgrid.com)
 
 ## Tutorial
 
-[Database Content Administration Application in 15 Lines of PHP Code](http://phpgrid.com/example/database-content-administration-application-15-lines-php-code/)
+Visit [Database Content Administration Application in 15 Lines of PHP Code](http://phpgrid.com/example/database-content-administration-application-15-lines-php-code/)
+
+![demo design](http://phpgrid.com/wp-content/uploads/2016/12/db-admin-mockup.png)