Personalize emails when double authentication is enabled

Customizing the email sent when connecting a user when the "passwordless" module is enabled

For the subject of the message it is possible to use ####SITENAME#### which allows to retrieve the name of the site.

add_filter('secupress.plugin.passwordless_email_subject', 'modify_passwordless_email_subject'); 
function modify_passwordless_email_subject() { 	
	return '[###SITENAME###] Secure Login Request'; 
}