Add Microsof Excel file formats to wiki config

Install/Templates/mediawiki/LocalSettings.php

@@ -151,7 +151,7 @@ wfLoadExtension( 'WikiEditor' );
 $wgSessionCacheType = CACHE_DB;
 
 # Add file extensions
-$wgFileExtensions = array('ppt', 'pptx', 'pdf', 'doc', 'docx', 'odt', 'odp', 'xml', 'json', 'jpg', 'png', 'jpeg', 'svg');
+$wgFileExtensions = array('ppt', 'pptx', 'pdf', 'doc', 'docx', 'odt', 'odp', 'xml', 'json', 'jpg', 'png', 'jpeg', 'svg', 'xls', 'xlsx', 'xlsm');
 
 # Enable extensions
 require_once "$IP/extensions/DrawioEditor/DrawioEditor.php";