GUACAMOLE-2139: Add automatic retrieval of license information where absent. Remove unused license info.

doc/licenses/apache-commons-digester/NOTICE

@@ -2,11 +2,12 @@
 # URL:     http://commons.apache.org/proper/commons-digester/
 # From:    'Apache Software Foundation' (https://www.apache.org/)
 # License: Apache v2.0
+# Source:  https://raw.githubusercontent.com/apache/commons-digester/refs/tags/DIGESTER_${_VERSION_}/NOTICE.txt
 #
-# --- BEGIN LICENSE FILE ---
+# --- BEGIN LICENSE FILE [1.8] ---
 Apache Jakarta Commons Digester
 Copyright 2001-2006 The Apache Software Foundation
 
 This product includes software developed by
 The Apache Software Foundation (http://www.apache.org/).
-# --- END LICENSE FILE ---
+# --- END LICENSE FILE [1.8] ---