Make small tweaks to launch node README

First of all, we're using RST syntax, so rename it to README.rst.

More importantly, remove menitons of puppetmaster - and puppet in
general, as they are distracting. When reading the file, my eyes
scanned and hit puppetmaster and I almost skipped the section with the
assumption it was out of date.

Change-Id: I294bf17084be7dad46e075ad2a3ef2674276c018

launch/README.rst

@@ -19,26 +19,24 @@ automatically, but it prints the commands to run). Note that for
 records via the printed commands. Forward A and AAAA records should
 be added to opendev/zone-opendev.org/zones/opendev.org/zone.db.
 
-In order for Ansible to be able to send out the Puppet updates,
-you also need the puppetmaster to accept the root SSH key for the
-new server. So as root on bridge.openstack.org:
+We need to add the host to our static inventory file so that
+the ansible runs see the new host. The launch script prints out
+the appropriate lines to add to
+opendev/system-config:inventory/openstack.yaml.
+
+In order for Ansible to work, you also need to accept the root SSH
+key for the new server. Once the new DNS entries have propagated,
+as root on bridge.openstack.org:
 
   ssh root@$FQDN
 
 Verify the fingerprint of the new server and type "yes" to accept.
 Then you can log out.
 
-Finally we need to add the host to our static inventory file so that
-the periodic ansible runs (which can run puppet) see the new host.
-Update opendev/system-config/inventory/openstack.yaml to
-include the appropriate hostname and IP address details.
-
 Add DNS Records
 ===============
 
-There are no scripts to automatically handle DNS at the moment due to
-a lack of library support for the new Rackspace Cloud DNS (with IPv6).
-However, the launch-node script will print the commands needed to be
+The launch-node script will print the commands needed to be
 run to configure DNS for a newly launched server.  To see the commands
 for an existing server, run: