Add FOSSA license scanning badge

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

README.md

@@ -3,6 +3,7 @@
 [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/4782/badge)](https://bestpractices.coreinfrastructure.org/projects/4782)
 [![e2e](https://github.com/fluxcd/flux2/workflows/e2e/badge.svg)](https://github.com/fluxcd/flux2/actions)
 [![report](https://goreportcard.com/badge/github.com/fluxcd/flux2)](https://goreportcard.com/report/github.com/fluxcd/flux2)
+[![FOSSA Status](https://app.fossa.com/api/projects/custom%2B162%2Fgithub.com%2Ffluxcd%2Fflux2.svg?type=shield)](https://app.fossa.com/projects/custom%2B162%2Fgithub.com%2Ffluxcd%2Fflux2?ref=badge_shield)
 [![license](https://img.shields.io/github/license/fluxcd/flux2.svg)](https://github.com/fluxcd/flux2/blob/main/LICENSE)
 [![release](https://img.shields.io/github/release/fluxcd/flux2/all.svg)](https://github.com/fluxcd/flux2/releases)
 [![Artifact HUB](https://img.shields.io/endpoint?url=https://artifacthub.io/badge/repository/flux2)](https://artifacthub.io/packages/helm/fluxcd-community/flux2)