Add cloud native index page

Cloud Native GitLab supports more than one ways to install GitLab.
Previously, we only had the charts, but we the addition of operator,
we need a central page to list all the cloud native ways to install
GitLab that will also serve as the landing page in the docs navbar.

doc/install/cloud_native/index.md

+---
+stage: Enablement
+group: Distribution
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
+comments: false
+description: Install GitLab in a cloud native environment
+type: index
+---
+
+# Cloud Native GitLab **(FREE SELF)**
+
+[Cloud Native GitLab](https://gitlab.com/gitlab-org/build/CNG) provides cloud
+native containers to deploy GitLab. These containers may be deployed and managed
+via Helm using GitLab Charts or GitLab Operator on Kubernetes, OpenShift,
+and Kubernetes compatible container platforms:
+
+- [Helm charts](https://docs.gitlab.com/charts/): The cloud native Helm chart
+  installs GitLab and all of its components on Kubernetes. Use this method if
+  your infrastructure is built on Kubernetes and you're familiar with how it
+  works. The methods for management, observability, and some concepts are
+  different than traditional deployments.
+- [GitLab Operator](https://docs.gitlab.com/operator/): The GitLab Operator
+  provides an installation and management method for GitLab following the
+  [Kubernetes Operator pattern](https://kubernetes.io/docs/concepts/extend-kubernetes/operator/).
+  You can also use the GitLab Operator to run GitLab in an
+  [OpenShift](../openshift_and_gitlab/index.md) environment.
+
+Here's an overview of how the containers are built:
+
+```mermaid
+graph TD
+  subgraph Code
+  CNG --> HC
+  CNG --> GOP
+  HC --> GOP
+  end
+
+  subgraph Deploy
+  GOP --> K8s
+  GOP --> OS
+  CNG --> DC
+  HC --> K8s
+  end
+
+  CNG[Cloud Native GitLab containers]
+  HC[Helm Chart]
+  K8s(Kubernetes)
+  GOP[GitLab Operator]
+  OS(OpenShift)
+  DC(Docker Compose)
+```

doc/install/index.md

@@ -29,10 +29,10 @@ install GitLab:
 |----------------------------------------------------------------|-------------|----------------|
 | [Linux package](https://docs.gitlab.com/omnibus/installation/) | The official deb/rpm packages (also known as Omnibus GitLab) that contains a bundle of GitLab and the components it depends on, including PostgreSQL, Redis, and Sidekiq. | This method is recommended for getting started. The Linux packages are mature, scalable, and are used today on GitLab.com. If you need additional flexibility and resilience, we recommend deploying GitLab as described in the [reference architecture documentation](../administration/reference_architectures/index.md). |
 | [Helm charts](https://docs.gitlab.com/charts/)                 | The cloud native Helm chart for installing GitLab and all of its components on Kubernetes. | When installing GitLab on Kubernetes, there are some trade-offs that you need to be aware of: <br/>- Administration and troubleshooting requires Kubernetes knowledge.<br/>- It can be more expensive for smaller installations. The default installation requires more resources than a single node Linux package deployment, as most services are deployed in a redundant fashion.<br/><br/> Use this method if your infrastructure is built on Kubernetes and you're familiar with how it works. The methods for management, observability, and some concepts are different than traditional deployments. |
-| [Docker](https://docs.gitlab.com/omnibus/docker/)              | The GitLab packages, Dockerized. | Use this method if you're familiar with Docker. |
+| [Docker](docker.md)              | The GitLab packages, Dockerized. | Use this method if you're familiar with Docker. |
 | [Source](installation.md)                                      | Install GitLab and all of its components from scratch. | Use this method if none of the previous methods are available for your platform. Useful for unsupported systems like \*BSD.|
 | [GitLab Environment Toolkit (GET)](https://gitlab.com/gitlab-org/gitlab-environment-toolkit#documentation) | The GitLab Environment Toolkit provides a set of automation tools to deploy a [reference architecture](../administration/reference_architectures/index.md) on most major cloud providers. | Customers are very welcome to trial and evaluate GET today, however be aware of [key limitations](https://gitlab.com/gitlab-org/gitlab-environment-toolkit#missing-features-to-be-aware-of) of the current iteration. For production environments further manual setup will be required based on your specific requirements. |
-| [GitLab Operator](https://docs.gitlab.com/charts/installation/operator.html)   | The GitLab Operator provides an installation and management method for GitLab following the [Kubernetes Operator pattern](https://kubernetes.io/docs/concepts/extend-kubernetes/operator/). | Use the GitLab Operator to run GitLab in an [OpenShift](openshift_and_gitlab/index.md) environment. |
+| [GitLab Operator](https://docs.gitlab.com/operator/)   | The GitLab Operator provides an installation and management method for GitLab following the [Kubernetes Operator pattern](https://kubernetes.io/docs/concepts/extend-kubernetes/operator/). | Use the GitLab Operator to run GitLab in an [OpenShift](openshift_and_gitlab/index.md) environment. |
 
 ## Install GitLab on cloud providers