Minor - fix function call.

main/document/document.php

@@ -1774,7 +1774,7 @@ if (isset($documentAndFolders) && is_array($documentAndFolders)) {
             }
 
             if ((isset($_GET['keyword']) &&
-                search_keyword($document_name, $_GET['keyword'])) ||
+                DocumentManager::search_keyword($document_name, $_GET['keyword'])) ||
                 !isset($_GET['keyword']) || empty($_GET['keyword'])
             ) {
                 $sortable_data[] = $row;

main/inc/lib/document.lib.php

@@ -5837,7 +5837,8 @@ class DocumentManager
      * Check if the file name or folder searched exist
      * @return return bool Return true when exist
      */
-    function search_keyword($document_name, $keyword) {
+    public static function search_keyword($document_name, $keyword)
+    {
         if (api_strripos($document_name, $keyword) !== false) {
             return true;
         } else {