Add license badge

Author: mblaschke

README.md

@@ -1,5 +1,6 @@
 # goreplace
 [![GitHub release](https://img.shields.io/github/release/webdevops/goreplace.svg)](https://github.com/webdevops/goreplace/releases)
+[![license](https://img.shields.io/github/license/webdevops/goreplace.svg)](https://github.com/webdevops/goreplace/blob/master/LICENSE)
 
 Cli utility for replacing text in files, written in golang and compiled for usage in Docker images