fix batching example to use new file param syntax

Author: Josh Pettett

examples/sendFilesWithBatching.php

@@ -8,9 +8,9 @@
 $params = array(
     'to' => $toNumber,
     'file' => array(
-        # Create files and put their names here prefixed with '@'
-        '@files/coverPage.html',
-        '@files/content.pdf'
+        # Use open file handles to upload files
+        fopen('files/coverPage.html', 'r'),
+        fopen('files/content.pdf', 'r')
     ),
     'batch_delay' => 60
 );