Minor - show creation date of a document.

main/document/edit_document.php

@@ -350,6 +350,7 @@ if (!empty($sessionId)) {
 
 $owner_id = $document_info['insert_user_id'];
 $last_edit_date = $document_info['lastedit_date'];
+$createdDate = $document_info['insert_date'];
 $groupInfo = GroupManager::get_group_properties(api_get_group_id());
 
 if ($owner_id == api_get_user_id() ||
@@ -412,6 +413,10 @@ if ($owner_id == api_get_user_id() ||
         }
     }
 
+    if (!empty($createdDate)) {
+        $form->addLabel(get_lang('CreatedOn'), Display::dateToStringAgoAndLongDate($createdDate));
+    }
+
     if (!$group_document && !DocumentManager::is_my_shared_folder(api_get_user_id(), $currentDirPath, $sessionId)) {
         $form->addLabel(get_lang('UpdatedOn'), Display::dateToStringAgoAndLongDate($last_edit_date));
     }