Use 'os_distro' instead of 'os-distro'

Change-Id: I4fd8c4db9f2297019ead053b97aa0c8c577864bb
Closes-Bug: #1676450

doc/source/dev/quickstart.rst

@@ -343,7 +343,7 @@ Upload the image to glance::
                         --public \
                         --disk-format=qcow2 \
                         --container-format=bare \
-                        --property os-distro=coreos \
+                        --property os_distro=coreos \
                         --file=coreos_production_openstack_image.img
 
 Create a CoreOS Kubernetes ClusterTemplate, which is similar to the Atomic
@@ -648,7 +648,7 @@ Alternatively, you can download and upload a pre-built image::
     wget https://fedorapeople.org/groups/magnum/ubuntu-mesos-latest.qcow2
     openstack image create ubuntu-mesos --public \
                         --disk-format=qcow2 --container-format=bare \
-                        --property os-distro=ubuntu --file=ubuntu-mesos-latest.qcow2
+                        --property os_distro=ubuntu --file=ubuntu-mesos-latest.qcow2
 
 Then, create a ClusterTemplate by using 'mesos' as the COE, with the rest of
 arguments similar to the Kubernetes ClusterTemplate::

doc/source/userguide.rst

@@ -98,9 +98,9 @@ They are loosely grouped as: mandatory, infrastructure, COE specific.
 
 --image \<image\>
   The name or UUID of the base image in Glance to boot the servers for
-  the cluster.  The image must have the attribute 'os-distro' defined
+  the cluster.  The image must have the attribute 'os_distro' defined
   as appropriate for the cluster driver.  For the currently supported
-  images, the os-distro names are:
+  images, the os_distro names are:
 
   ========== =====================
   COE        os-distro