doc(readme): add license scan status and report

Signed-off-by: xizhao <kevin@fossa.io>

README.md

@@ -2,6 +2,7 @@
 [![Build Status](https://travis-ci.org/vitessio/vitess.svg?branch=master)](https://travis-ci.org/vitessio/vitess/builds)
 [![codebeat badge](https://codebeat.co/badges/51c9a056-1103-4522-9a9c-dc623821ea87)](https://codebeat.co/projects/github-com-youtube-vitess)
 [![Go Report Card](https://goreportcard.com/badge/vitess.io/vitess)](https://goreportcard.com/report/vitess.io/vitess)
+[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fvitessio%2Fvitess.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fvitessio%2Fvitess?ref=badge_shield)
 [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/1724/badge)](https://bestpractices.coreinfrastructure.org/projects/1724)
 
 # Vitess 
@@ -40,3 +41,5 @@ for low-frequency updates like new features and releases.
 
 Unless otherwise noted, the Vitess source files are distributed
 under the Apache Version 2.0 license found in the LICENSE file.
+
+[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fvitessio%2Fvitess.svg?type=large)](https://app.fossa.io/projects/git%2Bgithub.com%2Fvitessio%2Fvitess?ref=badge_large)