Diagram(s) for ArgoCD Notifications

[brunocascio]

Discussed in https://github.com/argoproj/argo-cd/discussions/11577

Summary

Make some diagram explaining how argocd evaluates the argocd-notifications config map. How triggers and defaultTriggers are processed along with subscriptions and defaultSubscriptions.

Motivation

Have a better understanding of how the notifications controller's requests are processed

Proposal

• Flow Diagram and/or sequence diagram
• Steps performed by the algorithm

[korostelevm]

Also not clear how oncePer works, so far seems impossible to get a notfication for a deployment without getting false positives.

Manifests defined for a number of different apps in the same repo; when one of them is updated, all of them get synced.