Code coverage badge

Author: jsgm

README.md

@@ -2,5 +2,6 @@
 
 [![Go Reference](https://pkg.go.dev/badge/badge/github.com/jsgm/go-securitytxt.svg)](https://pkg.go.dev/github.com/jsgm/go-securitytxt)
 [![Go Report Card](https://goreportcard.com/badge/github.com/jsgm/go-securitytxt)](https://goreportcard.com/report/github.com/jsgm/go-securitytxt)
+[![codecov](https://codecov.io/gh/jsgm/go-securitytxt/graph/badge.svg?token=0KHAS1668J)](https://codecov.io/gh/jsgm/go-securitytxt)
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
 ![Last Commit](https://img.shields.io/github/last-commit/jsgm/go-securitytxt)