Note: Doc team updates the current version of the documentation and the
two previous versions (n-2), but we address *only high-priority, or
customer-reported issues* for -2 releases in support.
Describe the changes in the doc and link to your dev story:

1. - [X] Mandatory: Add the required version to the Fix version/s field.

2. - [X] Mandatory: Choose the type of documentation change or review.

• [X] We need to update to an existing topic

• [ ] We need to add a new document to an existing section

• [ ] We need a whole new section; this is a function not
  documented before and doesn't belong in any current section

• [ ] We need an Operator Advisory review and approval

• [ ] We need a z-Stream (Errata) Advisory and Release note
  for MCE and/or ACM

3. - [X] *Mandatory: *Use the following link to open the doc and find where the
documentation update should go. Note: As the feature and doc is
understood and developed, this placement decision may change:

• Published doc: https://docs.redhat.com/en/documentation/red_hat_advanced_cluster_management_for_kubernetes/2.12/html-single/clusters/index#release-images-specify
• Source: https://github.com/stolostron/rhacm-docs/blob/2.13_stage/clusters/cluster_lifecycle/release_images_specify.adoc

4. - [ ] Mandatory for GA content:

• [X] Add steps, the diff, known issue, and/or other important
  conceptual information in the following space:

ClusterImageSets are kept in a github repo (see https://access.redhat.com/articles/6961617). But when customers cannot reach github (perhaps disconnected), or their security policy doesn't allow it they may have to take additional steps. It would be great to have a list of external requirments for RHACM so they can prepare for this. But minimally, ii will help to have a link to our disconnected docs from this location to tell them how to do it. So, the request for this Jira is to add a note that calls this out, for instance (from chatgpt):

"By default, RHACM fetches OpenShift ClusterImageSets from a GitHub repository managed by Red Hat. These ClusterImageSets define OpenShift versions that can be deployed via RHACM. Access to this repository requires an internet connection to GitHub unless you configure your setup to use a mirrored or internal repository​. To set this up please review the steps as shared in our disconnected mage guide at https://docs.redhat.com/en/documentation/red_hat_advanced_cluster_management_for_kubernetes/2.12/html-single/clusters/index#release-images-disconnected. "

Or something better worded by a human

• [X] *Add Required access level *(example, *Cluster
  Administrator*) for the user to complete the task:

Cluster admin access is required I think, but whatever the docs state is fine and doesn't need to change.

• [X] Add verification at the end of the task, how does the user
  verify success (a command to run or a result to see?)

There is a visible link between the two docs.

• [ ] Add link to dev story here:

5. - [ ] Mandatory for bugs: What is the diff? Clearly define what the
problem is, what the change is, and link to the current documentation. Only
use this for a documentation bug.