Updated architecture diagram and edit wording

Changed figref to updated logical architecture diagram; minor edits to wording
in the OpenStack architecture section

Change-Id: I1e70fdaff67ead88fd5878497cbcd712a5902148
backport: none
Closes-Bug: #1283467

doc/training-guides/module001-ch004-openstack-architecture.xml

@@ -54,20 +54,19 @@
           ("Keystone")</para>
       </listitem>
     </itemizedlist>
-    <para>This is a stylized and simplified view of the architecture,
-      assuming that the implementer is using all of the services
-      together in the most common configuration. It also only shows
-      the "operator" side of the cloud -- it does not picture how
-      consumers of the cloud may actually use it. For example, many
-      users will access object storage heavily (and directly).</para>
+    <para>The conceptual diagram is a stylized and simplified view of the
+architecture. It assumes that the implementer uses all services in the most
+common configuration. It also shows only the operator side of the cloud; it
+does not show how consumers might use the cloud. For example, many
+users directly and heavily access object storage.</para>
   <para><guilabel>Logical Architecture</guilabel></para>
-    <para>This picture is consistent with the conceptual architecture
-      above:</para>
+    <para>The following diagram is consistent with the conceptual architecture
+as previously described:</para>
   <figure>
-    <title>Logical Diagram</title>
+    <title>Logical diagram</title>
     <mediaobject>
       <imageobject>
-        <imagedata fileref="figures/image31.jpg"/>
+        <imagedata fileref="figures/openstack-arch-havana-logical-v1.jpg"/>
       </imageobject>
     </mediaobject>
   </figure>