Fatal error when activating

Hi @mushlih!

I have installed the plugin and when I activate it, it returns a fatal error.

The problem is in line 11 of the Reference.php file:

require_once plugin_dir_path(__FILE__) . 'functions.php';

It is a simple typo: The capital letter is missing in the file name Functions.php.
After correcting the typo, the plugin is activated without problems and works correctly.

Thanks for your work!