Added Documentation for duplicateBehaviour option
diff --git a/src/main/java/org/apache/maven/plugins/assembly/mojos/AbstractAssemblyMojo.java b/src/main/java/org/apache/maven/plugins/assembly/mojos/AbstractAssemblyMojo.java
index c6a00ff..be1d507 100644
--- a/src/main/java/org/apache/maven/plugins/assembly/mojos/AbstractAssemblyMojo.java
+++ b/src/main/java/org/apache/maven/plugins/assembly/mojos/AbstractAssemblyMojo.java
@@ -318,6 +318,10 @@
      * <pre>
      * &lt;appxml&gt;${project.basedir}/somepath/app.xml&lt;/appxml&gt;
      * </pre>
+     * <p/>
+     * To set a method for dealing with duplicate files when creating the archive the &lt;duplicateBehavior&gt; tag 
+     * should be used with possible values of: fail, skip, or replace.
+     *
      *
      * @since 2.2-beta-3
      */