Document context hierarchy support in the TCF

This commit updates the reference manual regarding the new support for
@ContextHierarchy and hierarchy modes in @DirtiesContext.

Issue: SPR-10357

Author: sbrannen

src/reference/docbook/new-in-3.2.xml

@@ -274,6 +274,12 @@
         WebApplicationContext</link> in integration tests</para>
       </listitem>
 
+      <listitem>
+        <para>Configuring <link
+        linkend="testcontext-ctx-management-ctx-hierarchies">context hierarchies</link>
+        in integration tests</para>
+      </listitem>
+
       <listitem>
         <para>Testing <link linkend="testcontext-web-scoped-beans">request and
         session scoped beans</link></para>