OSSMDOC-335: Document lack of support for canary upgrades

Author: JStickler

modules/ossm-vs-istio.adoc

@@ -126,7 +126,16 @@ You can deploy virtual machines to OpenShift using OpenShift Virtualization. The
 [id="ossm-gateways_{context}"]
 == Gateways
 
-{SMProductName} installs ingress and egress gateways by default. You can disable this in the SMCP using `spec.gateways.ingress.enabled=false` or `spec.gateways.egress.enabled=false`.
+{SMProductName} installs ingress and egress gateways by default. You can disable gateway installation in the `ServiceMeshControlPlane` (SMCP) resource by using the following settings:
+
+* `spec.gateways.enabled=false` to disable both ingress and egress gateways.
+* `spec.gateways.ingress.enabled=false` to disable ingress gateways.
+* `spec.gateways.egress.enabled=false`  to disable egress gateways.
+
+[NOTE]
+====
+The Operator annotates the default gateways to indicate that they are generated by and managed by the {SMProductName} Operator.
+====
 
 [id="ossm-multicluster-configuration_{context}"]
 == Multicluster configurations

service_mesh/v2x/upgrading-ossm.adoc

@@ -28,7 +28,9 @@ endif::[]
 [id="upgrading-control-plane"]
 == Upgrading the Service Mesh control plane
 
-You must manually update the control plane for minor and major releases.
+You must manually update the control plane for minor and major releases. The community Istio project recommends canary upgrades, {SMProductName} only supports in-place upgrades. {SMProductName} requires that you upgrade from each minor release to the next minor release in sequence. For example, you must upgrade from version 2.0 to version 2.1, and then upgrade to version 2.2. You cannot update from {SMProductName} 2.0 to 2.2 directly.
+
+When you upgrade the service mesh control plane, all Operator managed resources, for example gateways, are also upgraded.
 
 include::modules/ossm-upgrade-21-22-changes.adoc[leveloffset=+2]