Add command to upgrade config controller image

Author: ajheflin

modules/upgrade-central-cluster-central.adoc

@@ -18,6 +18,14 @@ $ oc -n stackrox set image deploy/central central=registry.redhat.io/advanced-cl
 ----
 <1> If you use Kubernetes, enter `kubectl` instead of `oc`.
 
+* Run the following command to update the Config Controller image:
++
+[source,terminal,subs=attributes+]
+----
+$ oc -n stackrox set image deploy/config-controller central=registry.redhat.io/advanced-cluster-security/rhacs-main-rhel8:{rhacs-version} <1>
+----
+<1> If you use Kubernetes, enter `kubectl` instead of `oc`.
+
 
 .Verification