Create an informative issue (See each section, incomplete templates/issues won't be triaged)

Using the current documentation as a model, please complete the issue template. 

Note: Doc team updates the current version and the two previous versions (n-2). For earlier versions, we will address only high-priority, customer-reported issues for releases in support.

Prerequisite: Start with what we have

https://github.com/stolostron/rhacm-docs/blob/2.8_stage/clusters/cluster_lifecycle/create_cluster_on_prem.adoc describes how to deploy a cluster using the CLI (yaml), but leaves booting the host to the user.

The user can also boot the host using a Bare Metal Host as described in https://github.com/openshift/assisted-service/blob/290cea4b5f5bb10724d455a975e4da83e48ca8ef/docs/hive-integration/kube-api-getting-started.md#utilize-baremetalhost.

They need to ensure that the BMH is labeled with the correct infraenv and that the bootMACAddress matches an interface on the host.

We should also document the annotations available to control the discovered Agent spec. This is documented upstream here https://github.com/openshift/assisted-service/blob/290cea4b5f5bb10724d455a975e4da83e48ca8ef/docs/hive-integration/README.md#bare-metal-operator-integration

This should also include documenting the required ports should the user decide to use a BMH to boot their host.
This is currently documented as a part of bare-metal IPI, but we should either copy or link to that documentation here.
ref: https://docs.openshift.com/container-platform/4.13/installing/installing_bare_metal_ipi/ipi-install-prerequisites.html#network-requirements-out-of-band_ipi-install-prerequisites

Unfortunately several ports are currently missing from that doc. See https://issues.redhat.com/browse/OCPBUGS-17088 and https://issues.redhat.com/browse/OCPBUGS-18191

Describe the changes in the doc and link to your dev story

Provide info for the following steps:

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

2. - [x] Mandatory Choose the type of documentation change.

      - [x] New topic in an existing section or new section
      - [ ] Update to an existing topic

3. - [ ] Mandatory for GA content:
            
       - [x] Add steps and/or other important conceptual information here: 
        Users can add discover hosts for use by the infrastructure operator using BareMetalHost resources. We should document how this is done.
            
       - [x] Add Required access level for the user to complete the task here:
        User must have access to the Baseboard Management Controller credentials for the host to be added

       - [ ] Add verification at the end of the task, how does the user verify success (a command to run or a result to see?)
      The host will be discovered as an Agent resource and can be added to a cluster as a node
     
       - [ ] Add link to dev story here:

4. - [ ] Mandatory for bugs: What is the diff? Clearly define what the problem is, what the change is, and link to the current documentation: