fix course_log_default_extra_fields example

main/install/configuration.dist.php

@@ -225,7 +225,7 @@ $_configuration['system_stable'] = NEW_VERSION_STABLE;
 // For example, to show as a default column the user extra field with id 15 and 37 on site 1:
 // [1 => [15, 37]];
 // Same config plus site 3 and extra fields with id 53 and 55:
-// [1 => [15, 37], 2 => [53, 55]];
+// [1 => [15, 37], 3 => [53, 55]];
 //$_configuration['course_log_default_extra_fields'] = [1 => []];
 // Unoconv binary file
 //$_configuration['unoconv.binaries'] = '/usr/bin/unoconv';