Remove duplicated set of instructions

UX advises that the GKE and EKS instructions for adding a cluster
are identical, so we don't need to keep two separate copies.

doc/user/project/clusters/add_eks_clusters.md

@@ -59,6 +59,7 @@ To create and add a new Kubernetes cluster to your project, group, or instance:
    - Project's **{cloud-gear}** **Operations > Kubernetes** page, for a project-level cluster.
    - Group's **{cloud-gear}** **Kubernetes** page, for a group-level cluster.
    - **{admin}** **Admin Area >** **{cloud-gear}** **Kubernetes**, for an instance-level cluster.
+<br><br/>
 1. Click **Add Kubernetes cluster**.
 1. Under the **Create new cluster** tab, click **Amazon EKS**. You will be provided with an
    `Account ID` and `External ID` to use in the next step.
@@ -154,6 +155,7 @@ To create and add a new Kubernetes cluster to your project, group, or instance:
    - **Node count** - The number of worker nodes.
    - **GitLab-managed cluster** - Leave this checked if you want GitLab to manage namespaces and service accounts for this cluster.
      See the [Managed clusters section](index.md#gitlab-managed-clusters) for more information.
+<br><br/>
 1. Finally, click the **Create Kubernetes cluster** button.
 
 After about 10 minutes, your cluster will be ready to go. You can now proceed
@@ -201,112 +203,8 @@ you must create one.
 
 ## Existing EKS cluster
 
-To add an existing EKS cluster to your project, group, or instance:
-
-1. Perform the following steps on the EKS cluster:
-   1. Retrieve the certificate. A valid Kubernetes certificate is needed to authenticate to the
-      EKS cluster. We will use the certificate created by default.
-      Open a shell and use `kubectl` to retrieve it:
-
-      1. List the secrets with `kubectl get secrets`, and one should named similar to
-         `default-token-xxxxx`. Copy that token name for use below.
-      1. Get the certificate with:
-
-         ```shell
-         kubectl get secret <secret name> -o jsonpath="{['data']['ca\.crt']}" | base64 --decode
-         ```
-
-   1. Create admin token. A `cluster-admin` token is required to install and manage Helm Tiller.
-      GitLab establishes mutual SSL authentication with Helm Tiller and creates limited service
-      accounts for each application. To create the token we will create an admin service account as
-      follows:
-
-      1. Create a file called `eks-admin-service-account.yaml` with contents:
-
-         ```yaml
-         apiVersion: v1
-         kind: ServiceAccount
-         metadata:
-           name: eks-admin
-           namespace: kube-system
-         ```
-
-      1. Apply the service account to your cluster:
-
-         ```shell
-         $ kubectl apply -f eks-admin-service-account.yaml
-         serviceaccount "eks-admin" created
-         ```
-
-      1. Create a file called `eks-admin-cluster-role-binding.yaml` with contents:
-
-         ```yaml
-         apiVersion: rbac.authorization.k8s.io/v1beta1
-         kind: ClusterRoleBinding
-         metadata:
-           name: eks-admin
-         roleRef:
-           apiGroup: rbac.authorization.k8s.io
-           kind: ClusterRole
-           name: cluster-admin
-         subjects:
-         - kind: ServiceAccount
-           name: eks-admin
-           namespace: kube-system
-         ```
-
-      1. Apply the cluster role binding to your cluster:
-
-         ```shell
-         $ kubectl apply -f eks-admin-cluster-role-binding.yaml
-         clusterrolebinding "eks-admin" created
-         ```
-
-      1. Retrieve the token for the `eks-admin` service account:
-
-         ```shell
-         kubectl -n kube-system describe secret $(kubectl -n kube-system get secret | grep eks-admin | awk '{print $1}')
-         ```
-
-         Copy the `<authentication_token>` value from the output:
-
-         ```yaml
-         Name:         eks-admin-token-b5zv4
-         Namespace:    kube-system
-         Labels:       <none>
-         Annotations:  kubernetes.io/service-account.name=eks-admin
-                    kubernetes.io/service-account.uid=bcfe66ac-39be-11e8-97e8-026dce96b6e8
-
-         Type:  kubernetes.io/service-account-token
-
-         Data
-         ====
-         ca.crt:     1025 bytes
-         namespace:  11 bytes
-         token:      <authentication_token>
-         ```
-
-   1. Locate the API server endpoint so GitLab can connect to the cluster. This is displayed on
-      the AWS EKS console, when viewing the EKS cluster details.
-1. Navigate to your:
-   - Project's **{cloud-gear}** **Operations > Kubernetes** page, for a project-level cluster.
-   - Group's **{cloud-gear}** **Kubernetes** page, for a group-level cluster.
-   - **{admin}** **Admin Area >** **{cloud-gear}** **Kubernetes** page, for an instance-level cluster.
-1. Click **Add Kubernetes cluster**.
-1. Click the **Add existing cluster** tab and fill in the details:
-   - **Kubernetes cluster name**: A name for the cluster to identify it within GitLab.
-   - **Environment scope**: Leave this as `*` for now, since we are only connecting a single cluster.
-   - **API URL**: The API server endpoint retrieved earlier.
-   - **CA Certificate**: The certificate data from the earlier step, as-is.
-   - **Service Token**: The admin token value.
-   - For project-level clusters, **Project namespace prefix**: This can be left blank to accept the
-     default namespace, based on the project name.
-1. Click on **Add Kubernetes cluster**. The cluster is now connected to GitLab.
-
-At this point, [Kubernetes deployment variables](index.md#deployment-variables) will
-automatically be available during CI/CD jobs, making it easy to interact with the cluster.
-
-If you would like to utilize your own CI/CD scripts to deploy to the cluster, you can stop here.
+For information on adding an existing EKS cluster, see
+[Existing Kubernetes cluster](add_remove_clusters.md#existing-kubernetes-cluster).
 
 ### Create a default Storage Class
 

doc/user/project/clusters/add_remove_clusters.md

@@ -158,15 +158,16 @@ Kubernetes integration is not supported for arm64 clusters. See the issue
 To add a Kubernetes cluster to your project, group, or instance:
 
 1. Navigate to your:
-   - Project's **{cloud-gear}** **Operations > Kubernetes** page, for a project-level cluster.
-   - Group's **{cloud-gear}** **Kubernetes** page, for a group-level cluster.
-   - **{admin}** **Admin Area >** **{cloud-gear}** **Kubernetes** page, for an instance-level cluster.
+   1. Project's **{cloud-gear}** **Operations > Kubernetes** page, for a project-level cluster.
+   1. Group's **{cloud-gear}** **Kubernetes** page, for a group-level cluster.
+   1. **{admin}** **Admin Area >** **{cloud-gear}** **Kubernetes** page, for an instance-level cluster.
+<br></br>
 1. Click **Add Kubernetes cluster**.
 1. Click the **Add existing cluster** tab and fill in the details:
-   - **Kubernetes cluster name** (required) - The name you wish to give the cluster.
-   - **Environment scope** (required) - The
+   1. **Kubernetes cluster name** (required) - The name you wish to give the cluster.
+   1. **Environment scope** (required) - The
       [associated environment](index.md#setting-the-environment-scope-premium) to this cluster.
-   - **API URL** (required) -
+   1. **API URL** (required) -
       It's the URL that GitLab uses to access the Kubernetes API. Kubernetes
       exposes several APIs, we want the "base" URL that is common to all of them.
       For example, `https://kubernetes.example.com` rather than `https://kubernetes.example.com/api/v1`.
@@ -177,10 +178,10 @@ To add a Kubernetes cluster to your project, group, or instance:
       kubectl cluster-info | grep 'Kubernetes master' | awk '/http/ {print $NF}'
       ```
 
-   - **CA certificate** (required) - A valid Kubernetes certificate is needed to authenticate to the cluster. We will use the certificate created by default.
-     - List the secrets with `kubectl get secrets`, and one should be named similar to
+   1. **CA certificate** (required) - A valid Kubernetes certificate is needed to authenticate to the cluster. We will use the certificate created by default.
+      1. List the secrets with `kubectl get secrets`, and one should be named similar to
          `default-token-xxxxx`. Copy that token name for use below.
-     - Get the certificate by running this command:
+      1. Get the certificate by running this command:
 
          ```shell
 
@@ -192,7 +193,7 @@ To add a Kubernetes cluster to your project, group, or instance:
          If the command returns the entire certificate chain, you need copy the *root ca*
          certificate at the bottom of the chain.
 
-   - **Token** -
+   1. **Token** -
       GitLab authenticates against Kubernetes using service tokens, which are
       scoped to a particular `namespace`.
       **The token used should belong to a service account with
@@ -279,10 +280,10 @@ To add a Kubernetes cluster to your project, group, or instance:
      documentation](https://cloud.google.com/iam/docs/granting-changing-revoking-access)
      to grant access.
 
-   - **GitLab-managed cluster** - Leave this checked if you want GitLab to manage namespaces and service accounts for this cluster.
+   1. **GitLab-managed cluster** - Leave this checked if you want GitLab to manage namespaces and service accounts for this cluster.
       See the [Managed clusters section](index.md#gitlab-managed-clusters) for more information.
 
-   - **Project namespace** (optional) - You don't have to fill it in; by leaving
+   1. **Project namespace** (optional) - You don't have to fill it in; by leaving
       it blank, GitLab will create one for you. Also:
       - Each project should have a unique namespace.
       - The project namespace is not necessarily the namespace of the secret, if
@@ -291,7 +292,7 @@ To add a Kubernetes cluster to your project, group, or instance:
       - If you or someone created a secret specifically for the project, usually
         with limited permissions, the secret's namespace and project namespace may
         be the same.
-
+<br></br>
 1. Finally, click the **Create Kubernetes cluster** button.
 
 After a couple of minutes, your cluster will be ready to go. You can now proceed