add missing trusted_apps key

Author: ylebre

config.php.example

@@ -25,6 +25,10 @@
 	// won't be locked out after failed login attempts;
 	const TRUSTED_IPS = [];
 
+	// Array of app origins that are automatically trusted. Useful for
+	// the test suite :)
+	const TRUSTED_APPS = [];
+
 	// Minimum entropy level for a password to be acceptable.
 	const MINIMUM_PASSWORD_ENTROPY = 15;