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.

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

3. - [x] Mandatory for GA content:
            
       - [x] Add steps and/or other important conceptual information here: 
       This is an update to the release notes for 2.9.0 for a known bug (ACM-8593) and its workaround.  The bug relates to hosted control planes with the agent platform.  HyperShift will periodically rotate the token used by the agent to pull ignition.  This bug causes the new token not to be propagated.  If you have an Agent resource that was created some time ago and is failing to pull ignition, you may have hit this bug.  The workaround is to delete the Secret referenced by the IgnitionEndpointTokenReference property in the Agent's spec, and then add or modify any label on the Agent resource.  At this point, the system will notice that the Agent resource was modified, and will recreate the Secret with the new token.
            
       - [x] Add Required access level for the user to complete the task here:
       Cluster owner

       - [x] Add verification at the end of the task, how does the user verify success (a command to run or a result to see?)
     The agent should now be able to pull ignition and be ready for installation.
     
       - [ ] Add link to dev story here: