Docs: encourage users to run apt-get dist-upgrade on target hosts

Ubuntu 14.04 is currently provided in several point releases, most
currently 14.04.3.  It is possible that users may initially deploy
roles on a previous point release of Ubuntu, and then later upgrade
system packages.  Most notably, br_netfilter is implemented in it's
own kernel module in kernel versions >= 3.18.  This results in ansible
fact caches being out of date on subsequent runs, and has caused a few
bugs to be filed along the way.

This patch is to hopefully ensure that users are using the most recent
version of packages when beginning with openstack-ansible.

Change-Id: I1fd4f11fc2e4be4fa4335f63031f7b2bdb312d34
Closes-Bug: #1535075

doc/source/developer-docs/quickstart-aio.rst

@@ -46,6 +46,14 @@ should you need to customize your build:
 * Initial host bootstrap
 * Run playbooks
 
+If you are building an AIO on a new server, it is recommended you first
+upgrade all system packages and reboot into the new kernel:
+
+   .. code-block:: shell-session
+
+       # apt-get dist-upgrade
+       # reboot
+
 Start by cloning the OpenStack-Ansible repository and changing into the
 repository root directory:
 

doc/source/install-guide/targethosts-prepare.rst

@@ -19,8 +19,14 @@ adding the Secure Shell (SSH) server packages to the installation.
 Configuring the operating system
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Check the kernel version, install additional software packages, and
-configure NTP.
+Upgrade system packages, check the kernel version, install additional
+software packages, and configure NTP.
+
+#. Upgrade system packages and kernel:
+
+   .. code-block:: shell-session
+
+       # apt-get dist-upgrade
 
 #. Check the kernel version. It should be ``3.13.0-34-generic`` or
    later.
@@ -43,7 +49,7 @@ configure NTP.
 
 #. Configure NTP to synchronize with a suitable time source.
 
-#. Reboot the host to activate the changes.
+#. Reboot the host to activate the changes and use new kernel.
 
 Deploying SSH keys
 ~~~~~~~~~~~~~~~~~~