I am sorry, in my file config.inc.php (in the directory config) I can't find this section. In the directory config I see more files: config.inc.php, defaults.inc.php, mimetypes.php and config.inc.php.sample.
The file mimetypes.php starts with
<?php
/**
* Local mapping file to specify mime-types based on common file-name extensions
*
* Please note that this mapping takes precedence over the content-based mime-type detection
* and should only contain mappings which cannot be detected properly from the file contents.
*/
return array(
'xls' => 'application/vnd.ms-excel',
'xlm' => 'application/vnd.ms-excel',
'xla' => 'application/vnd.ms-excel',
(and many more lines)
What do I have to do?