Index button is a feature that you can use to add a new action button on the top of the module.
|label||This key is used to provide naming the button label|
|icon||This key is used to provide an icon on the button, you can use FontAwesome|
|url||This key is used URL that will be addressed when the user presses the button|
$this->index_button = ["label"=>"Print Report","icon"=>"fa fa-print","url"=>CRUDBooster::mainpath('print-report')];
CRUDBooster :: mainpath () is inherited from CRUDBooster helper to generate Base URL of the relevant module.