Use XSD

Author: garydgregory

src/changes/changes.xml

@@ -35,7 +35,9 @@ mvn changes:announcement-generate -Prelease-notes [-Dchanges.version=m.n]
 The <action> type attribute can be add,update,fix,remove.
 -->
 
-<document>
+<document xmlns="http://maven.apache.org/changes/1.0.0"
+          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+          xsi:schemaLocation="http://maven.apache.org/changes/1.0.0 http://maven.apache.org/xsd/changes-1.0.0.xsd">
   <properties>
     <title>Apache Commons Codec Release Notes</title>
     <author>Apache Commons Developers</author>