Update istioctl docs (#7502)

* Update istioctl docs

* Lint

* Update content/en/docs/setup/install/istioctl/index.md

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

* Update content/en/docs/setup/install/istioctl/index.md

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

* Update content/en/docs/setup/install/istioctl/index.md

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

* Update content/en/docs/setup/install/istioctl/index.md

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

* Update content/en/docs/setup/install/istioctl/index.md

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

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

content/en/docs/setup/install/istioctl/index.md

@@ -40,6 +40,11 @@ using the following command:
 $ istioctl install
 {{< /text >}}
 
+{{< tip >}}
+Note that `istioctl install` and `istioctl manifest apply` are exactly the same command. In Istio 1.6, the simpler `install`
+command replaces `manifest apply`, which is deprecated and will be removed in 1.7.
+{{< /tip >}}
+
 This command installs the `default` profile on the cluster defined by your
 Kubernetes configuration. The `default` profile is a good starting point
 for establishing a production environment, unlike the larger `demo` profile that
@@ -83,6 +88,13 @@ to install the `demo` profile:
 $ istioctl install --set profile=demo
 {{< /text >}}
 
+## Check what's installed
+
+The `istioctl` command saves the `IstioOperator` CR that was used to install Istio in a copy of the CR named `installed-state`.
+You can inspect this CR if you lose track of what is installed in a cluster.
+
+The `installed-state` CR is also used to perform checks in some `istioctl` commands and should therefore not be removed.
+
 ## Display the list of available profiles
 
 You can display the names of Istio configuration profiles that are
@@ -182,28 +194,21 @@ $ istioctl profile diff default demo
 ## Generate a manifest before installation
 
 You can generate the manifest before installing Istio using the `manifest generate`
-sub-command, instead of `istioctl install`.
+sub-command.
 For example, use the following command to generate a manifest for the `default` profile:
 
 {{< text bash >}}
 $ istioctl manifest generate > $HOME/generated-manifest.yaml
 {{< /text >}}
 
-Inspect the manifest as needed, then apply the manifest using this command:
+The generated manifest can be used to inspect what exactly is installed as well as to track changes to the manifest
+over time. While the `IstioOperator` CR represents the full user configuration and is sufficient for tracking it,
+the output from `manifest generate` also captures possible changes in the underlying charts and therefore can be
+used to track the actual installed resources.
 
-{{< text bash >}}
-$ kubectl create ns istio-system
-$ kubectl apply -f $HOME/generated-manifest.yaml
-{{< /text >}}
-
-{{< warning >}}
-While `istioctl install` will automatically detect environment specific settings from your Kubernetes context, `manifest generate` cannot as it runs offline, which may lead to unexpected results. In particular, you must ensure that you follow [these steps](/docs/ops/best-practices/security/#configure-third-party-service-account-tokens) if your Kubernetes environment does not support third party service account tokens.
-{{< /warning >}}
-
-{{< tip >}}
-This command might show transient errors due to resources not being available in
-the cluster in the correct order.
-{{< /tip >}}
+The output from `manifest generate` can also be used to install Istio using `kubectl apply` or equivalent. However,
+these alternative installation methods may not apply the resources with the same sequencing of dependencies as
+`istioctl install` and are not tested in an Istio release.
 
 ## Show differences in manifests
 

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

@@ -11,8 +11,7 @@ This guide installs Istio using the standalone Istio
 [operator](https://kubernetes.io/docs/concepts/extend-kubernetes/operator/).
 The only dependencies required are a supported Kubernetes cluster, the `kubectl` command at the version to match the cluster, and the `istioctl` command at the desired release version.
 
-To install Istio for production use, we recommend [installing with {{< istioctl >}}](/docs/setup/install/istioctl/)
-instead.
+The operator is beta in 1.6 and suitable for production use.
 
 ## Prerequisites