Add a note that Serverless does not support multi-tenancy

Author: rh-max

serverless/install/install-serverless-operator.adoc

@@ -13,6 +13,11 @@ This guide walks cluster administrators through installing the {ServerlessOperat
 {ServerlessProductName} is supported for installation in a restricted network environment. For more information, see xref:../../operators/admin/olm-restricted-networks.adoc#olm-restricted-networks[Using Operator Lifecycle Manager on restricted networks].
 ====
 
+[NOTE]
+====
+{ServerlessProductName} currently cannot be used in a multi-tenant configuration on a single cluster.
+====
+
 include::modules/serverless-cluster-sizing-req.adoc[leveloffset=+1]
 
 If you have high availability (HA) enabled on your cluster, this requires between 0.5 - 1.5 cores and between 200MB - 2GB of memory for each replica of the Knative Serving control plane.