chore(README): add license scan badge (#6808)

* Add license scan report and status

Signed-off-by: fossabot <badges@fossa.io>

Author: fossabot

README.md

@@ -8,6 +8,7 @@
 [![devDependencies Status](https://david-dm.org/angular-ui/ui-grid/dev-status.svg)](https://david-dm.org/angular-ui/ui-grid?type=dev)
 [![OpenCollective](https://opencollective.com/ui-grid/backers/badge.svg)](#backers)
 [![OpenCollective](https://opencollective.com/ui-grid/sponsors/badge.svg)](#sponsors)
+[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fangular-ui%2Fui-grid.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fangular-ui%2Fui-grid?ref=badge_shield)
 
 [![Selenium Test Status](https://saucelabs.com/browser-matrix/nggrid.svg)](https://saucelabs.com/u/nggrid)