mqseries: remove useless wrapping para tag around &warn.experimental; (#5172)

Author: Girgias

reference/mqseries/book.xml

@@ -9,8 +9,8 @@
  <!-- {{{ preface -->
  <preface xml:id="intro.mqseries">
   &reftitle.intro;
+  &warn.experimental;
   <para>
-   &warn.experimental;
    This extension aims to provide an interface for communicating with IBMs
    WebSphere MQ series Queue managers.
   </para>