Add compact ShiftStack installation assembly

Resolves OSDOCS-11637

Author: maxwelldb

_topic_maps/_topic_map.yml

@@ -484,6 +484,8 @@ Topics:
     File: installing-openstack-user
   - Name: Installing a cluster on OpenStack in a restricted network
     File: installing-openstack-installer-restricted
+  - Name: Installing a three-node cluster on OpenStack
+    File: installing-openstack-three-node
   - Name: Configuring network settings after installing OpenStack
     File: installing-openstack-network-config
   - Name: OpenStack Cloud Controller Manager reference guide

installing/installing_openstack/installing-openstack-three-node.adoc

@@ -0,0 +1,17 @@
+:_mod-docs-content-type: ASSEMBLY
+[id="installing-openstack-three-node"]
+= Installing a three-node cluster on OpenStack
+include::_attributes/common-attributes.adoc[]
+:context: installing-openstack-three-node
+
+toc::[]
+
+In {product-title} version {product-version}, you can install a three-node cluster on {rh-openstack-first}. A three-node cluster consists of three control plane machines, which also act as compute machines. This type of cluster provides a smaller, more resource efficient cluster, for cluster administrators and developers to use for testing, development, and production.
+
+You can install a three-node cluster by using either installer-provisioned or user-provisioned infrastructure.
+
+include::modules/installation-three-node-cluster-cloud-provider.adoc[leveloffset=+1]
+
+== Next steps
+* xref:../../installing/installing_openstack/installing-openstack-installer-custom.adoc#installing-openstack-installer-custom[Installing a cluster on OpenStack with customizations]
+* xref:../../installing/installing_openstack/installing-openstack-user.adoc#installing-openstack-user[Installing a cluster on OpenStack on your own infrastructure]