Added that config jar is required to use the namespace.

docs/manual/src/docbook/namespace-config.xml

@@ -28,7 +28,8 @@
       that are available. We would recommend that you try out the <link
         xlink:href="http://www.springsource.com/products/sts">SpringSource Tool Suite</link> as it
       has special features for working with standard Spring namespaces. </para>
-    <para> To start using the security namespace in your application context, all you need to do is
+    <para> To start using the security namespace in your application context, you first need to make
+        sure that the <literal>spring-security-config</literal> jar is on your classpath. Then all you need to do is
       add the schema declaration to your application context file: <programlisting language="xml">
   <![CDATA[
 <beans xmlns="http://www.springframework.org/schema/beans"
@@ -37,7 +38,7 @@
   xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
           http://www.springframework.org/schema/security
-          http://www.springframework.org/schema/security/spring-security-3.0.xsd">
+          http://www.springframework.org/schema/security/spring-security-3.0.3.xsd">
     ...
 </beans>
   ]]></programlisting> In many of the examples you will see (and in the sample) applications, we
@@ -52,7 +53,7 @@
   xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
            http://www.springframework.org/schema/security
-           http://www.springframework.org/schema/security/spring-security-3.0.xsd">
+           http://www.springframework.org/schema/security/spring-security-3.0.3.xsd">
     ...
 </beans:beans>
 ]]></programlisting> We'll assume this syntax is being used from now on in this chapter. </para>