Update README.md

Author: doong-jo

README.md

@@ -5,5 +5,13 @@
     <img alt="typescript" src="https://camo.githubusercontent.com/71182b7c92d3c36c24eae5342f373d773d58c11d/68747470733a2f2f666c61742e62616467656e2e6e65742f62616467652f69636f6e2f54797065643f69636f6e3d74797065736372697074266c6162656c266c6162656c436f6c6f723d626c756526636f6c6f723d353535353535" />
     <img alt="Cypress.io tests" src="https://img.shields.io/badge/cypress.io-tests-green.svg" />
     <img alt="Jest" src="https://jestjs.io/img/jest-badge.svg" />
+    <a href="https://codecov.io/gh/doong-jo/react-t2m-timer">
+      <img alt="CodeCov" src="https://codecov.io/gh/doong-jo/react-t2m-timer/branch/master/graph/badge.svg" />
+    </a>
+    <a href="https://github.com/doong-jo/react-t2m-timer/actions">
+      <img alt="GitHub Action" src="https://github.com/doong-jo/react-t2m-timer/workflows/Deploy%20to%20GitHub%20Pages/badge.svg" />
+    </a>
     <img alt="License: MIT" src="https://img.shields.io/badge/License-MIT-green.svg" />
 </p>
+
+![preview](https://kr.object.ncloudstorage.com/etc/react-t2m-timer-preview.png)