Epic Goal

Add docs to demonstrate Multiple Sources feature for ArgoCD Application.

Background (Required)

Many of the OpenShift customers use Multiple Sources feature for ArgoCD Application. As we add support for the feature, users would be very much interested for the documentation for testing the feature.
The Multiple Sources feature was promoted from beta to Stable in ArgoCD v2.13. We would mark the feature GA in GitOps v1.15.

Approach (Required)

There is a document written for Openshift Routes, we could follow the same format for describing multiple sources feature. https://docs.google.com/document/d/1IwnK7NWLt3KNM1kihY4aDfP-tBLFuK4JN6g4qi4wGUY/edit 

Reference documents and blogs:

• https://developers.redhat.com/articles/2023/02/20/multiple-sources-argo-cd-applications#
• https://argo-cd.readthedocs.io/en/latest/user-guide/multiple_sources/
• https://blog.argoproj.io/draft-argo-cd-v2-6-release-candidate-ced1853bbfdb

Acceptance Criteria (Mandatory)

• Write a document which talks about the configuration and usage of ArgoCD Application with Multiple Sources.
• Document can assume that the user already has OpenShift GitOps Operator and ArgoCD installed.
• The document can be in the form of a Google doc, which we can provide to doc folks to get it into the OpenShift GitOps release docs