Added warnings regarding networking updates for Icehouse

I added several warnings informing users about potential structure
and/or content issues during the update process for Icehouse. I will
remove these warnings after we complete the process.

Change-Id: Ic13fbbdf60005d5e87ce90e7f3eb225e7e5d5698
Partial-Bug: #1291071

doc/install-guide/ch_basics.xml

@@ -4,7 +4,10 @@
   xml:id="ch_basics">
   <?dbhtml-stop-chunking?>
   <title>Basic operating system configuration</title>
-
+  <warning>
+    <para>We are updating this material for Icehouse. You may find structure
+      and/or content issues during this process.</para>
+  </warning>
   <para>This guide shows you how to create a controller node to host
     most services and a compute node to run virtual machine instances.
     Subsequent chapters create additional nodes to run more services.

doc/install-guide/ch_neutron.xml

@@ -4,6 +4,7 @@
     xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
     xml:id="ch_neutron">
     <title>Add the Networking service</title>
+<!-- FIXME Temporarily replacing this warning.
     <warning>
         <para>This chapter is a bit more adventurous than we would
             like. We are working on cleanup and improvements to it.
@@ -11,6 +12,11 @@
             through bug reports and patches to improve it are
             welcome.</para>
     </warning>
+-->
+    <warning>
+      <para>We are updating this material for Icehouse. You may find structure
+        and/or content issues during this process.</para>
+    </warning>
     <section xml:id="neutron-considerations">
         <title>Networking considerations</title>
         <para>OpenStack Networking drivers range from software bridges

doc/install-guide/ch_overview.xml

@@ -4,6 +4,10 @@
   xml:id="ch_overview">
   <?dbhtml stop-chunking?>
   <title>Architecture</title>
+  <warning>
+    <para>We are updating this material for Icehouse. You may find structure
+      and/or content issues during this process.</para>
+  </warning>
   <para>This install guide offers a few of the many ways to install
     <glossterm>OpenStack</glossterm> components and have them work together.
     It is meant as a

doc/install-guide/section_nova-boot.xml

@@ -3,6 +3,10 @@
   xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
   xml:id="nova-boot">
   <title>Launch an instance</title>
+  <warning>
+    <para>We are updating this material for Icehouse. You may find structure
+      and/or content issues during this process.</para>
+  </warning>
   <para>After you configure the Compute services, you can launch an
     instance. An instance is a virtual machine that OpenStack
     provisions on a Compute server. This example shows you

doc/install-guide/section_nova-network.xml

@@ -3,6 +3,10 @@
   xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
   xml:id="nova-network">
   <title>Configure networking</title>
+  <warning>
+    <para>We are updating this material for Icehouse. You may find structure
+      and/or content issues during this process.</para>
+  </warning>
   <para>Configuring networking in OpenStack can be a bewildering experience. The
     following example shows the simplest production-ready
     configuration that is available: the legacy networking in