added github actions badge

Author: AlexHaxe

README.md

@@ -3,6 +3,7 @@
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](http://opensource.org/licenses/MIT)
 [![Release](https://img.shields.io/github/release/HaxeCheckstyle/haxe-checkstyle.svg)](http://lib.haxe.org/p/checkstyle/)
 [![Build Status](https://travis-ci.org/HaxeCheckstyle/haxe-checkstyle.svg)](https://travis-ci.org/HaxeCheckstyle/haxe-checkstyle)
+[![Haxe-Checkstyle Linux](https://github.com/HaxeCheckstyle/haxe-checkstyle/workflows/Haxe-Checkstyle%20Linux/badge.svg)](https://codeclimate.com/github/HaxeCheckstyle/haxe-checkstyle/actions)
 [![Codecov](https://img.shields.io/codecov/c/github/HaxeCheckstyle/haxe-checkstyle.svg)](https://codecov.io/github/HaxeCheckstyle/haxe-checkstyle?branch=dev)
 <!-- [![Code Climate](https://codeclimate.com/github/HaxeCheckstyle/haxe-checkstyle/badges/gpa.svg)](https://codeclimate.com/github/HaxeCheckstyle/haxe-checkstyle)
 [![Code Climate Issues](https://img.shields.io/codeclimate/issues/HaxeCheckstyle/haxe-checkstyle.svg)](https://codeclimate.com/github/HaxeCheckstyle/haxe-checkstyle/issues)