Add link to graphical doc

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@163951 c90b9560-bf6c-de11-be94-00142212c4b1

reference/spl/reference.xml

@@ -1,5 +1,5 @@
 <?xml version='1.0' encoding='iso-8859-1'?>
-<!-- $Revision: 1.2 $ -->
+<!-- $Revision: 1.3 $ -->
  <reference id="ref.spl">
   <title>Standard PHP Library (SPL) Functions</title>
   <titleabbrev>spl</titleabbrev>
@@ -9,7 +9,13 @@
     &reftitle.intro;
     <para>
      SPL is a collection of interfaces and classes that are meant to solve
-     standard problems.
+     standard problems. 
+    </para>
+    <tip>
+     <para>
+      A more detailed documentation of SPL can be found
+      <ulink url="http://www.php.net/~helly/php/ext/spl/">here</ulink>.
+     </para>
     </para>
    </section>
    <section id="spl.installation">