docs: Add Snyk status badge to README.md (#12517)

Signed-off-by: Yuan Tang <[email protected]>
(cherry picked from commit 5cded3a)

README.md

@@ -1,5 +1,6 @@
 <!-- markdownlint-disable-next-line MD041 -->
 [![slack](https://img.shields.io/badge/slack-argoproj-brightgreen.svg?logo=slack)](https://argoproj.github.io/community/join-slack)
+[![Security Status](https://github.com/argoproj/argo-workflows/workflows/Snyk/badge.svg)](https://github.com/argoproj/argo-workflows/actions/workflows/snyk.yml?query=branch%3Amain)
 [![OpenSSF Best Practices](https://bestpractices.coreinfrastructure.org/projects/3830/badge)](https://bestpractices.coreinfrastructure.org/projects/3830)
 [![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/argoproj/argo-workflows/badge)](https://api.securityscorecards.dev/projects/github.com/argoproj/argo-workflows)
 [![FOSSA License Status](https://app.fossa.com/api/projects/git%2Bgithub.com%2Fargoproj%2Fargo-workflows.svg?type=shield)](https://app.fossa.com/projects/git%2Bgithub.com%2Fargoproj%2Fargo-workflows?ref=badge_shield)