Minor structure edits for control plane arch

Author: adellape

_topic_maps/_topic_map.yml

@@ -66,7 +66,7 @@ Topics:
 - Name: Installation and update
   Distros: openshift-enterprise,openshift-origin
   File: architecture-installation
-- Name: The control plane
+- Name: Control plane architecture
   File: control-plane
   Distros: openshift-enterprise,openshift-origin,openshift-online
 - Name: Understanding OpenShift development

architecture/control-plane.adoc

@@ -1,39 +1,39 @@
 :_content-type: ASSEMBLY
 [id="control-plane"]
-= The {product-title} control plane
+= Control plane architecture
 include::modules/common-attributes.adoc[]
 :context: control-plane
 
 toc::[]
 
-include::modules/understanding-control-plane.adoc[leveloffset=+1]
+The _control plane_, which is composed of control plane machines, manages the {product-title} cluster. The control plane machines manage workloads on the compute machines, which are also known as worker machines. The cluster itself manages all upgrades to the machines by the actions of the Cluster Version Operator (CVO), the Machine Config Operator, and a set of individual Operators.
 
-include::modules/architecture-machine-config-pools.adoc[leveloffset=+2]
+include::modules/architecture-machine-config-pools.adoc[leveloffset=+1]
 
 .Additional resources
 
 * For more information on configuration drift detection, see xref:../post_installation_configuration/machine-configuration-tasks.adoc#machine-config-drift-detection_post-install-machine-configuration-tasks[Understanding configuration drift detection].
 
-include::modules/architecture-machine-roles.adoc[leveloffset=+2]
+include::modules/architecture-machine-roles.adoc[leveloffset=+1]
 
-include::modules/operators-overview.adoc[leveloffset=+2]
+include::modules/operators-overview.adoc[leveloffset=+1]
 
 ifdef::openshift-enterprise,openshift-webscale,openshift-origin[]
-include::modules/arch-platform-operators.adoc[leveloffset=+3]
+include::modules/arch-platform-operators.adoc[leveloffset=+2]
 .Additional resources
 
 * For an index of CVO-managed Operators, see xref:../operators/operator-reference.adoc#platform-operators-ref[Platform Operators reference].
 endif::[]
 
-include::modules/arch-olm-operators.adoc[leveloffset=+3]
+include::modules/arch-olm-operators.adoc[leveloffset=+2]
 .Additional resources
 
 * For more details on running add-on Operators in {product-title}, see the _Operators_ guide sections on xref:../operators/understanding/olm/olm-understanding-olm.adoc#olm-understanding-olm[Operator Lifecycle Manager (OLM)] and xref:../operators/understanding/olm-understanding-operatorhub.adoc#olm-understanding-operatorhub[OperatorHub].
 * For more details on the Operator SDK, see xref:../operators/operator_sdk/osdk-about.adoc#osdk-about[Developing Operators].
 
-include::modules/update-service-overview.adoc[leveloffset=+3]
+include::modules/update-service-overview.adoc[leveloffset=+1]
 
-include::modules/understanding-machine-config-operator.adoc[leveloffset=+3]
+include::modules/understanding-machine-config-operator.adoc[leveloffset=+1]
 
 .Additional information
 

modules/understanding-control-plane.adoc

@@ -1,8 +1,8 @@
 // Module included in the following assemblies:
 //
 // * architecture/control-plane.adoc
-[id="understanding-machine-config-operator_{context}"]
-= Understanding the Machine Config Operator
+[id="about-machine-config-operator_{context}"]
+= About the Machine Config Operator
 
 {product-title} {product-version} integrates both
 operating system and cluster management. Because the cluster manages its own