Fix small typo in the docs

This closes #35

activemq-broker/src/main/java/org/apache/activemq/security/AuthenticationUser.java

@@ -17,10 +17,10 @@
 package org.apache.activemq.security;
 
 /**
- * A helper object used to configure simple authentiaction plugin
- * 
+ * A helper object used to configure simple authentication plugin
+ *
  * @org.apache.xbean.XBean
- * 
+ *
  */
 public class AuthenticationUser {
 
@@ -60,5 +60,4 @@ public class AuthenticationUser {
     public void setUsername(String username) {
         this.username = username;
     }
-
 }