Description

Document epic: GitOps integration using pull model (https://issues.redhat.com/browse/ACM-1301)

Draft documentation is available here: https://docs.google.com/document/d/1zC0QJwPdYeQlJcfIVdBRYOvoFcH4Moo8b9liZi9F5Kk/edit#

Development Complete

• The code is complete.
• Functionality is working.
• Any required downstream Docker file changes are made.

Tests Automated

• [ ] Unit/function tests have been automated and incorporated into the
  build.
• [ ] 100% automated unit/function test coverage for new or changed APIs.

Secure Design

• [ ] Security has been assessed and incorporated into your threat model.

Multidisciplinary Teams Readiness

• [ ] Create an informative documentation issue using the [Customer
  Portal_doc_issue template](
  https://github.com/stolostron/backlog/issues/new?assignees=&labels=squad%3Adoc&template=doc_issue.md&title=),
  and ensure doc acceptance criteria is met. Link the development issue to
  the doc issue.
• [ ] Provide input to the QE team, and ensure QE acceptance criteria
  (established between story owner and QE focal) are met.

Support Readiness

• [ ] The must-gather script has been updated.

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

Always look at the current documentation to describe the change that is needed. Use the source or portal link for Step 3:

 - Use the Customer Portal: https://access.redhat.com/documentation/en-us/red_hat_advanced_cluster_management_for_kubernetes/2.6

 - Use the GitHub link to find the staged docs in the repository: https://github.com/stolostron/rhacm-docs 

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

Provide info for the following steps:

 1. - [ ] Mandatory Choose the type of documentation change.

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

2. - [ ] Mandatory for GA content:
            
       - [ ] Add steps and/or other important conceptual information here: 
       https://docs.google.com/document/d/1zC0QJwPdYeQlJcfIVdBRYOvoFcH4Moo8b9liZi9F5Kk
            
       - [ ] Add Required access level for the user to complete the task here:
       User needs to be in subscription-admin role

       - [ ] Add verification at the end of the task, how does the user verify success (a command to run or a result to see?)
     The applicationSetReport, described in https://docs.google.com/document/d/1zC0QJwPdYeQlJcfIVdBRYOvoFcH4Moo8b9liZi9F5Kk, is used to verify if an ArgoCD applicationset, deployed using the pull model, was successful or not.
     
       - [ ] Add link to dev story here:

https://issues.redhat.com/browse/ACM-1301