BZ-2087151: Added note about specifying a priority class name for hosted control planes

Author: bergerhoffer

modules/nodes-descheduler-installing.adoc

@@ -18,6 +18,11 @@ The descheduler is not available by default. To enable the descheduler, you must
 
 By default, the descheduler runs in predictive mode, which means that it only simulates pod evictions. You must change the mode to automatic for the descheduler to perform the pod evictions.
 
+[IMPORTANT]
+====
+If you have enabled hosted control planes in your cluster, set a custom priority threshold to lower the chance that pods in the hosted control plane namespaces are evicted. Set the priority threshold class name to `hypershift-control-plane`, because it has the lowest priority value (`100000000`) of the hosted control plane priority classes.
+====
+
 .Prerequisites
 
 * Cluster administrator privileges.