Merge pull request #5847 from ministryofjustice/upgrade-updates

docs: ✏️ update cluster upgrade docs

runbooks/source/eks-cluster.html.md.erb

@@ -166,3 +166,9 @@ terraform apply
 ```
 
 [cluster build pipeline]: https://concourse.cloud-platform.service.justice.gov.uk/teams/main/pipelines/create-cluster
+
+# Provisiong a custom cluster
+
+If you working on a task that involves changing/adding cluster configuration or components, you can have Concourse execute a clean cluster build for you based off your working infrastructure branch. Refer to the instructions detailed in the Concourse repository [pipelines README](https://github.com/ministryofjustice/cloud-platform-terraform-concourse/blob/main/pipelines/README.md#custom-cluster-pipeline) for the steps to follow.
+
+Once you're done with your customised cluster, you can have Concourse delete it for you using the branch flag of the [CLI delete-cluster command](https://runbooks.cloud-platform.service.justice.gov.uk/delete-cluster.html#delete-the-cluster-with-concourse-delete-cluster-pipeline).

runbooks/source/upgrade-eks-cluster.html.md.erb

@@ -1,7 +1,7 @@
 ---
 title: Upgrade EKS cluster
 weight: 53
-last_reviewed_on: 2024-04-10
+last_reviewed_on: 2024-07-05
 review_in: 6 months
 ---
 
@@ -35,6 +35,10 @@ Before you begin, there are a few pre-requisites:
 
 - Run [kubent](https://github.com/doitintl/kube-no-trouble) against cluster to find deprecated APIs.
 
+## Creating Cluster Upgrade GitHub Issues
+
+In order to help maintain a clear process for steps to follow in carrying out a cluster upgrade, we have an [issue template](https://github.com/ministryofjustice/cloud-platform/blob/main/.github/ISSUE_TEMPLATE/cloud-platform-k8s-upgrade-template.md) which is used by [this script](https://github.com/ministryofjustice/cloud-platform/blob/main/cmd/create-upgrade-issues/main.go) to create individual issues for each step of the upgrade process. As you work through these issues, its helpful to review and update the template where necessary to ensure it remains relevant for future upgrades.
+
 ## Upgrade Steps
 
 ### Compatibility Check