GUACAMOLE-773: Bring license details of bundled Java dependencies up-to-date.

doc/licenses/apache-santuario-2.2.0/NOTICE

@@ -0,0 +1,12 @@
+Apache Santuario - XML Security for Java
+Copyright 1999-2020 The Apache Software Foundation
+
+This product includes software developed at
+The Apache Software Foundation (http://www.apache.org/).
+
+It was originally based on software copyright (c) 2001, Institute for
+Data Communications Systems, <http://www.nue.et-inf.uni-siegen.de/>.
+
+The development of this software was partly funded by the European 
+Commission in the <WebSig> project in the ISIS Programme. 
+