Document usage of multiple namespaces

Author: Sergey Dudoladov

README.md

@@ -74,7 +74,7 @@ All subsequent `kubectl` commands will work with the `test` namespace. The opera
 
 Watching a namespace for an operator means tracking requests to change Postgresql clusters in the namespace such as "increase the number of Postgresql replicas to 5" and reacting to the requests, in this example by actually scaling up. 
 
-By default, the operator watches the namespace it is deployed to. You can change this by altering the `WATCHED_NAMESPACE` env var in the operator deployment manifest or the `watched_namespace` field in the operator configmap. In the case both are set, the env var takes the precedence.
+By default, the operator watches the namespace it is deployed to. You can change this by altering the `WATCHED_NAMESPACE` env var in the operator deployment manifest or the `watched_namespace` field in the operator configmap. In the case both are set, the env var takes the precedence. To make the operator listen to all namespaces, explicitly set the field/env var to "`*`".
 
 Note that for an operator to manage pods in the watched namespace, the operator's service account (as specified in the operator deployment manifest) has to have appropriate privileges to access the watched namespace. The watched namespace also needs to have a (possibly different) service account in the case database pods need to talk to the Kubernetes API (e.g. when using Kubernetes-native configuration of Patroni).