Added CI build status in the README

Author: iTrooz

README.md

@@ -1,3 +1,7 @@
+<p align="center">
+  <a title="'Build' workflow Status" href="https://github.com/maharmstone/btrfs/actions?query=workflow%3ABuild%20CI"><img alt="'Build workflow Status" src="https://img.shields.io/github/workflow/status/maharmstone/btrfs/Build%20CI?longCache=true&style=for-the-badge&label=Build&logoColor=fff&logo=GitHub%20Actions"></a>
+</p> 
+
 WinBtrfs v1.8
 -------------