README.md correction in create_folder

[whitneyscott]

The following lines in the README.md file don't work in my PHP code:

`<?php
// folder is created in the root folder.
SproutVideo\Folder.create_folder(array('name' => 'New Folder'));

// folder is created as a child of the folder specified by the id 'def456'
SproutVideo\Folder.create_folder(array(
'name' => 'New Folder',
'parent_id' => 'def456'
));
?>This does work:<?php
// folder is created in the root folder.
SproutVideo\Folder::create_folder(array('name' => 'New Folder'));

// folder is created as a child of the folder specified by the id 'def456'
SproutVideo\Folder::create_folder(array(
'name' => 'New Folder',
'parent_id' => 'def456'
));
?>`