[release-1.6] Add a clause indicating that CNI works OOB (#7560)

* Add a clause indicating that CNI works OOB

CNI should work nearly everywhere out of the box. If someone or
something provides a nonstandard configuration, the existing documentation
can help them get moving.

* Update content/en/docs/setup/additional-setup/cni/index.md

LGTM @frankb.

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

Co-authored-by: Steven Dake <sdake@ibm.com>
Co-authored-by: Steven Dake <steven.dake@gmail.com>
Co-authored-by: Frank Budinsky <frankb@ca.ibm.com>

content/en/docs/setup/additional-setup/cni/index.md

@@ -42,7 +42,29 @@ replaces the functionality provided by the `istio-init` container.
     *  The Kubernetes documentation highly recommends this for all Kubernetes installations
        where `ServiceAccounts` are utilized.
 
-## Installation
+## Basic Installation
+
+In most environments, a basic Istio cluster with CNI enabled can be installed using the following command:
+
+{{< text bash >}}
+$ cat <<EOF > istio-cni.yaml
+apiVersion: install.istio.io/v1alpha1
+kind: IstioOperator
+spec:
+  components:
+    cni:
+      enabled: true
+  values:
+    cni:
+      excludeNamespaces:
+       - istio-system
+       - kube-system
+      logLevel: info
+EOF
+$ istioctl install -f istio-cni.yaml
+{{< /text >}}
+
+## Advanced Installation
 
 1.  Determine the Kubernetes environment's CNI plugin `--cni-bin-dir` and `--cni-conf-dir` settings.
     Refer to [Hosted Kubernetes settings](#hosted-kubernetes-settings) for any non-default settings required.