Adding missing content to the gitops-docs-main repo

[Dhruv-Soni11]

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GitOps-docs-main

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Release Note updates for GITOPS-5010 , GITOPS-4358

Updates in the Aggregated cluster roles section. The 1st bullet in the Important Note is updated.

Updates in the Create user-defined cluster roles and configure user-defined permissions section. A small change is made in the first paragraph.

Fixing old links in the Additional resources section of the Managing the application set resources in non-control plane namespaces

Fixing the incorrect backtick of the default value <default_Argo_CD_Known_Hosts> of the initialSSHKnownHosts property in the Argo CD custom resource properties table

Fixing an incorrectly rendered attribute in the Using Argo Rollouts for progressive deployment delivery section.

QE review:

• [ ] QE has approved this change.

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