Updating documentation for argocd high-availability configuration

General MR

Summary

Updating documentation for argocd architecture document after configuring, deploying and testing a highly-available configuration of ArgoCD.

constraints such as the argocd-dev-server were documented to reflect components of ArgoCD that do not support HA.

Testing

After configuring for HA, the cypress tests were run locally to replicate adding and syncing projects. These ran without errors.

Issues

Closes #1278 (closed)

BB Processes

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