Fix #69399: Serializable and __wakeup()

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@339383 c90b9560-bf6c-de11-be94-00142212c4b1

language/predefined/serializable.xml

@@ -25,6 +25,13 @@
     a constructor instead of calling __construct(). If you need to execute the standard
     constructor you may do so in the method.
    </para>
+   <para>
+    Note, that when an old instance of a class that implements this interface
+    now, which had been serialized before the class implemeted the interface, is
+    unserialized, <link linkend="object.wakeup">__wakeup()</link> is called
+    instead of the serialize method, what might be useful for migration
+    purposes.
+   </para>
   </section>
 <!-- }}} -->