Merge pull request #90331 from subhtk/ocp17709

OCPBUGS#17709: Updated nodes labels section

Author: maxwelldb

modules/nodes-nodes-working-updating.adoc

@@ -60,3 +60,10 @@ For example:
 ----
 $ oc label pods --all status=unhealthy
 ----
+
+[IMPORTANT]
+====
+In {product-title} 4.12 and later, newly installed clusters include both the `node-role.kubernetes.io/control-plane` and `node-role.kubernetes.io/master` labels on control plane nodes by default.
+
+In {product-title} versions earlier than 4.12, the `node-role.kubernetes.io/control-plane` label is not added by default. Therefore, you must manually add the `node-role.kubernetes.io/control-plane` label to control plane nodes in clusters upgraded from earlier versions.
+====