Add overview and preview note

Author: jhlodin

src/current/v25.2/configure-cockroachdb-kubernetes-operator.md

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 This page explains how to configure Kubernetes cluster resources such as memory, CPU, and storage.
 
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 On a production cluster, the resources you allocate to CockroachDB should be proportionate to your machine types and workload. Cockroach Labs recommends that you determine and set these values before deploying the cluster, but you can also update the values on a running cluster.
 
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src/current/v25.2/deploy-cockroachdb-with-kubernetes-operator.md

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 This page describes how to start and stop a secure 3-node CockroachDB cluster in a single [Kubernetes](http://kubernetes.io/) cluster.
 
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 ## Prerequisites and best practices
 
 ### Kubernetes version

src/current/v25.2/deploy-cockroachdb-with-kubernetes.md

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 This page shows you how to start and stop a secure 3-node CockroachDB cluster in a single [Kubernetes](http://kubernetes.io/) cluster. You can use any of the following approaches:
 
-- [CockroachDB Kubernetes Operator](https://github.com/cockroachdb/cockroach-operator)
+- [Public Kubernetes operator](https://github.com/cockroachdb/cockroach-operator)
 
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     The CockroachDB Kubernetes Operator is also available on platforms such as [Red Hat OpenShift]({% link {{ page.version.version }}/deploy-cockroachdb-with-kubernetes-openshift.md %}) and [IBM Cloud Pak for Data](https://www.ibm.com/products/cloud-pak-for-data).
@@ -36,7 +36,7 @@ This page shows you how to start and stop a secure 3-node CockroachDB cluster in
 Choose how you want to deploy and maintain the CockroachDB cluster.
 
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-The [CockroachDB Kubernetes Operator](https://github.com/cockroachdb/cockroach-operator) eases CockroachDB cluster creation and management on a single Kubernetes cluster.
+The [Public Kubernetes operator](https://github.com/cockroachdb/cockroach-operator) eases CockroachDB cluster creation and management on a single Kubernetes cluster.
 
 The Operator does not provision or apply an Enterprise license key. To use CockroachDB with the Operator, [set a license]({% link {{ page.version.version }}/licensing-faqs.md %}#set-a-license) in the SQL shell.
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src/current/v25.2/kubernetes-operator-overview.md

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 key: operate-cockroachdb-kubernetes-operator.html
 ---
 
-Placeholder content introducing the new operator and comparing it to existing k8s deployments.
+The CockroachDB operator is a fully-featured [Kubernetes operator](https://kubernetes.io/docs/concepts/extend-kubernetes/operator/) that allows you to deploy and manage CockroachDB self-hosted clusters.
+
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+With the CockroachDB operator, you can deploy CockroachDB clusters across multiple regions with separate operator instances per region. Using [Helm](https://helm.sh/), set configurations that manage the operator and CockroachDB nodes across regions.
+
+## CockroachDB operator
+
+This section describes how to:
+
+- [Deploy a CockroachDB cluster using the CockroachDB operator]({% link {{page.version.version}}/deploy-cockroachdb-with-kubernetes-operator.md %}).
+- Migrate from an existing CockroachDB Kubernetes deployment using [Helm]({% link {{page.version.version}}/migrate-cockroachdb-kubernetes-helm.md %}) or the [public operator]({% link {{page.version.version}}/migrate-cockroachdb-kubernetes-operator.md %}).
+- Operate a CockroachDB cluster:
+
+    - [Manage pod scheduling]({% link {{page.version.version}}/schedule-cockroachdb-kubernetes-operator.md %}).
+    - [Manage cluster resources]({% link {{page.version.version}}/configure-cockroachdb-kubernetes-operator.md %}).
+    - [Manage certificates]({% link {{page.version.version}}/secure-cockroachdb-kubernetes-operator.md %}).
+    - [Scale a cluster]({% link {{page.version.version}}/scale-cockroachdb-kubernetes-operator.md %}).
+    - [Monitor a cluster]({% link {{page.version.version}}/monitor-cockroachdb-kubernetes-operator.md %}).
+    - [Upgrade a cluster]({% link {{page.version.version}}/upgrade-cockroachdb-kubernetes-operator.md %}).
+    - [Improve cluster performance]({% link {{page.version.version}}/kubernetes-operator-performance.md %}).
+
+## Kubernetes terminology
+
+Before starting, review some basic Kubernetes terminology. Note that CockroachDB [nodes]({% link {{ page.version.version }}/architecture/glossary.md %}#cockroachdb-architecture-terms) are distinct from Kubernetes "nodes" or "worker nodes".
+
+Feature | Description
+--------|------------
+[node](https://kubernetes.io/docs/concepts/architecture/nodes/) | A physical or virtual machine. In the [deployment guide]({% link {{ page.version.version }}/deploy-cockroachdb-with-kubernetes-operator.md %}), you'll create instances and join them as worker nodes into a single Kubernetes cluster.
+[pod](http://kubernetes.io/docs/user-guide/pods/) | A pod is a group of one of more Docker containers. In the [deployment guide]({% link {{ page.version.version }}/deploy-cockroachdb-with-kubernetes-operator.md %}), each pod will run on a separate Kubernetes worker node and include one Docker container running a single CockroachDB node, reflecting our [topology recommendations]({% link {{ page.version.version }}/recommended-production-settings.md %}#topology).
+[operator](https://kubernetes.io/docs/concepts/extend-kubernetes/operator/) | An operator is an extension to Kubernetes that uses custom resources to efficiently manage specific applications. The CockroachDB operator includes two custom resource definitions, `cockroachdb` to manage a CockroachDB pod and `operator` to manage the operator pod itself. Unlike the older [public operator](https://github.com/cockroachdb/cockroach-operator), the CockroachDB operator does not use StatefulSets and is designed to simplify multi-region deployments.
+[persistent volume](http://kubernetes.io/docs/user-guide/persistent-volumes/) | A persistent volume is a piece of networked storage (Persistent Disk on GCE, Elastic Block Store on AWS) mounted into a pod. The lifetime of a persistent volume is decoupled from the lifetime of the pod that's using it, ensuring that each CockroachDB node binds back to the same storage on restart.<br><br>The [deployment guide]({% link {{ page.version.version }}/deploy-cockroachdb-with-kubernetes-operator.md %}) assumes that dynamic volume provisioning is available. When that is not the case, [persistent volume claims](http://kubernetes.io/docs/user-guide/persistent-volumes/#persistentvolumeclaims) need to be created manually.
+[RBAC](https://kubernetes.io/docs/reference/access-authn-authz/rbac/) | RBAC, or Role-Based Access Control, is the system Kubernetes uses to manage permissions within the cluster. In order to take an action (e.g., `get` or `create`) on an API resource (e.g., a `pod`), the client must have a `Role` that allows it to do so. The [deployment guide]({% link {{ page.version.version }}/deploy-cockroachdb-with-kubernetes-operator.md %}) creates the RBAC resources necessary for CockroachDB to create and access certificates.

src/current/v25.2/kubernetes-operator-performance.md

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 Kubernetes provides many useful abstractions for deploying and operating distributed systems, but some of the abstractions come with a performance overhead and an increase in underlying system complexity. This page outlines potential bottlenecks when running CockroachDB in Kubernetes and how to optimize performance.
 
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 ## Before you begin
 
 Before you focus on optimizing a Kubernetes-orchestrated CockroachDB cluster:

src/current/v25.2/migrate-cockroachdb-kubernetes-helm.md

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 This guide describes how to migrate an existing CockroachDB cluster managed via StatefulSet to the CockroachDB operator.
 
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 These instructions assume that you are migrating from a StatefulSet cluster that was configured using the Helm chart with the following command:
 
 ~~~ shell

src/current/v25.2/migrate-cockroachdb-kubernetes-operator.md

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 This guide describes how to migrate an existing CockroachDB cluster managed via the public operator to the CockroachDB operator.
 
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 These instructions assume that you are migrating from a public operator cluster that is managed with kubectl via the following yaml files:
 
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src/current/v25.2/monitor-cockroachdb-kubernetes-operator.md

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 Despite CockroachDB's various [built-in safeguards against failure](architecture/replication-layer.html), it is critical to actively monitor the overall health and performance of a cluster running in production and to create alerting rules that promptly send notifications when there are events that require investigation or intervention.
 
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 ## Configure Prometheus
 
 Every node of a CockroachDB cluster exports granular timeseries metrics formatted for easy integration with [Prometheus](https://prometheus.io/), an open source tool for storing, aggregating, and querying timeseries data. This section shows you how to orchestrate Prometheus as part of your Kubernetes cluster and pull these metrics into Prometheus for external monitoring.

src/current/v25.2/scale-cockroachdb-kubernetes-operator.md

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 This page explains how to add and remove CockroachDB nodes on Kubernetes.
 
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 ## Add nodes
 
 Before scaling up CockroachDB, note the following [topology recommendations](recommended-production-settings.html#topology):

src/current/v25.2/schedule-cockroachdb-kubernetes-operator.md

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 This page describes how to configure pod scheduling settings. These settings control how CockroachDB pods should be identified or scheduled onto worker nodes, which are then proxied to the Kubernetes scheduler.
 
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 ## Node selectors
 
 A pod with a *node selector* will be scheduled onto a worker node that has matching [labels](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/), or key-value pairs.