When editing a document show the author information if exists.

- Get "insert_user_id" field and show the author's information
- Use Display::dateToStringAgoAndLongDate instead of custom code.

main/document/edit_document.php

@@ -413,10 +413,14 @@ if ($owner_id == api_get_user_id() ||
     }
 
     if (!$group_document && !DocumentManager::is_my_shared_folder(api_get_user_id(), $currentDirPath, $sessionId)) {
-        // Updated on field
-        $display_date = date_to_str_ago($last_edit_date).
-            ' <span class="dropbox_date">'.api_format_date(api_get_local_time($last_edit_date)).'</span>';
-        $form->addElement('static', null, get_lang('UpdatedOn'), $display_date);
+        $form->addLabel(get_lang('UpdatedOn'), Display::dateToStringAgoAndLongDate($last_edit_date));
+    }
+
+    if (!empty($document_info['insert_user_id'])) {
+        $insertByUserInfo = api_get_user_info($document_info['insert_user_id']);
+        if (!empty($insertByUserInfo)) {
+            $form->addLabel(get_lang('Author'), $insertByUserInfo['complete_name_with_message_link']);
+        }
     }
 
     $form->addElement('textarea', 'comment', get_lang('Comment'), ['cols-size' => [2, 10, 0]]);