Add example to watch multiple namespaces for istio operator (#7571)

* Add example to watch multiple namespaces for istio operator

* Rename istioNamespace to watchedNamespaces

* Add suggestion

Co-authored-by: Frank Budinsky <frankb@ca.ibm.com>

* Remove deprecated flag

* Move paragraph as per suggestion

Co-authored-by: Frank Budinsky <frankb@ca.ibm.com>

* Few more improvements

Co-authored-by: Frank Budinsky <frankb@ca.ibm.com>

Co-authored-by: Frank Budinsky <frankb@ca.ibm.com>

content/en/docs/setup/install/standalone-operator/index.md

@@ -34,8 +34,13 @@ The operator is beta in 1.6 and suitable for production use.
     - A service to access operator metrics
     - Necessary Istio operator RBAC rules
 
-    See the available `istioctl operator init` flags to control which namespaces the controller and Istio are installed
-    into and the installed Istio image sources and versions.
+    You can configure which namespace the operator controller is installed in, the namespace(s) the operator watches, the installed Istio image sources and versions, and more. For example, you can pass one or more namespaces to watch using the `--watchedNamespaces` flag:
+
+    {{< text bash >}}
+    $ istioctl operator init --watchedNamespaces=istio-namespace1,istio-namespace2
+    {{< /text >}}
+
+    See the [`istioctl operator init` command reference](/docs/reference/commands/istioctl/#istioctl-operator-init) for details.
 
     {{< tip >}}
     You can alternatively deploy the operator using Helm:
@@ -45,7 +50,7 @@ The operator is beta in 1.6 and suitable for production use.
       --set hub=docker.io/istio \
       --set tag={{< istio_full_version >}} \
       --set operatorNamespace=istio-operator \
-      --set istioNamespace=istio-system | kubectl apply -f -
+      --set watchedNamespaces=istio-system | kubectl apply -f -
     {{< /text >}}
 
     Note that you need to [download the Istio release](/docs/setup/getting-started/#download)