Update README.md

Add build status

README.md

@@ -1,7 +1,7 @@
 What is Notepad++ ?
 ===================
 
-[![GitHub release](https://img.shields.io/github/release/notepad-plus-plus/notepad-plus-plus.svg)](../../releases/latest)
+[![GitHub release](https://img.shields.io/github/release/notepad-plus-plus/notepad-plus-plus.svg)](../../releases/latest)    [![Build Status](https://img.shields.io/github/actions/workflow/status/notepad-plus-plus/notepad-plus-plus/CI_build.yml)](https://github.com/notepad-plus-plus/notepad-plus-plus/actions/workflows/CI_build.yml)
     [![Join the discussions at https://community.notepad-plus-plus.org/](https://notepad-plus-plus.org/assets/images/NppCommunityBadge.svg)](https://community.notepad-plus-plus.org/)
 
 Notepad++ is a free (free as in both "free speech" and "free beer") source code