Proposed title of this feature request

• Make namespaces of argocd cluster-secret configurable in configmap. Doc

What are the nature and description of the request?

• Currently if we want to add a namespace on a remote cluster, we need to decrypt the secret, add the namespace, and then reencrypt the secret. And all this only to add a new namespace. If we could configure the namespaces (which are not sensitive information) in a configmap instead of a secret the whole process would be easier. 

Why does the customer need this? (List the business requirements here)

• Currently if we want to add a namespace on a remote cluster, we need to decrypt the secret, add the namespace, and then reencrypt the secret. And all this only to add a new namespace. If we could configure the namespaces (which are not sensitive information) in a configmap instead of a secret the whole process would be easier.