Update README.md

Author: khoih-prog

README.md

@@ -5,6 +5,7 @@
 [![GitHub](https://img.shields.io/github/license/mashape/apistatus.svg)](https://github.com/khoih-prog/ESPAsync_WiFiManager/blob/master/LICENSE)
 [![contributions welcome](https://img.shields.io/badge/contributions-welcome-brightgreen.svg?style=flat)](#Contributing)
 [![GitHub issues](https://img.shields.io/github/issues/khoih-prog/ESPAsync_WiFiManager.svg)](http://github.com/khoih-prog/ESPAsync_WiFiManager/issues)
+[![star this repo](https://githubbadges.com/star.svg?user=khoih-prog&repo=ESPAsync_WiFiManager&style=default)](https://github.com/khoih-prog/ESPAsync_WiFiManager)
 
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