SEC-624: Added section on 'getting the source' for reference from samples chapter

src/docbkx/introduction.xml

@@ -283,4 +283,26 @@
         changes in the PATCH level are perfectly compatible, forwards and
         backwards.</quote></para>
 </sect1>
+    
+<sect1 xml:id="get-source">
+    <title>Getting the Source</title>
+    <para>
+        Since Spring Security is an Open Source project, we'd strongly encourage you to 
+        check out the source code using subversion. This will give you full access to all the sample
+        applications and you can build the most up to date version of the project easily.
+        Having the source for a project is also a huge help in debugging. Exception stack traces are no 
+        longer obscure black-box issues but you can get straight to the line that's causing the problem
+        and work out what's happening. The source is the ultimate documentation for a project and often 
+        the simplest place to find out how something actually works.
+    </para>
+    <para>
+        To obtain the source for the project trunk, use the following subversion command:
+<programlisting>
+    svn checkout http://acegisecurity.svn.sourceforge.net/svnroot/acegisecurity/spring-security/trunk/
+</programlisting>
+        You can checkout specific versions from <literal>http://acegisecurity.svn.sourceforge.net/svnroot/acegisecurity/spring-security/tags/</literal>.
+    </para>
+    
+</sect1>
+
 </chapter>