Make a migration guide for moving services to ArgoCD

Overview

When we created our ArgoCD Proof-of-Concept, we migrated only the Sentry service. As we migrate more services, we should write a guide for moving services currently hosted in tanka, kubernetes-management, or gitlab-helmfiles to Argo. This should facilitate both our initial migration, and future services to be included.

Proposal

Write a guide in runbooks with steps to migrate a service. This should include

• steps to include a service in argo
• guidance on autosync
• how to remove the service from its current management

Exit criteria

• Helm migration docs written
• Tanka migration docs written