Hi,
Actually the file is included in the normal install. However due to default file permissions for the libraries files on Joomla, the existing helper.php file cannot get over-written. Hence the alternate (recommended) solution where you manually overwrite the helper.php (as illustrated in the documentation - under the Patch Menu files section). This is a temporal solution, as we currently working on a plugin that would replace that file patch approach for our upcoming release.
Cheers,
Kobby.