docs: add artifact badge (argoproj#2331)

Signed-off-by: zachaller <[email protected]>

Signed-off-by: zachaller <[email protected]>

README.md

@@ -3,6 +3,7 @@
 [![codecov](https://codecov.io/gh/argoproj/argo-rollouts/branch/master/graph/badge.svg)](https://codecov.io/gh/argoproj/argo-rollouts)
 [![slack](https://img.shields.io/badge/slack-argoproj-brightgreen.svg?logo=slack)](https://argoproj.github.io/community/join-slack)
 [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/3834/badge)](https://bestpractices.coreinfrastructure.org/projects/3834)
+[![Artifact HUB](https://img.shields.io/endpoint?url=https://artifacthub.io/badge/repository/argo-rollouts)](https://artifacthub.io/packages/helm/argo/argo-rollouts)
 
 ## What is Argo Rollouts?
 Argo Rollouts is a Kubernetes controller and set of CRDs which provide advanced deployment capabilities such as blue-green, canary, canary analysis, experimentation, and progressive delivery features to Kubernetes.