Created method setXMLTag_archivierbar in Dokument class

This method appends an XML tag named 'archivierbar' with value 'true' to
the XML data.

include/dokument_export.class.php

@@ -575,5 +575,11 @@ class dokument_export
 			}
 		}
 	}
+	
+	public function setXMLTag_archivierbar()
+	{
+		$archivierbar = $this->xml_data->createElement("archivierbar", "true");
+		$this->xml_data->documentElement->appendChild($archivierbar);
+	}
 }
 ?>