website: fix coverage status badges url error.

Author: jaywcjlove

www/src/Button.tsx

@@ -78,7 +78,7 @@ export const Badges = () => {
         <img alt="npm bundle size" src="https://img.shields.io/bundlephobia/minzip/@uiw/react-md-editor" />
       </a>
       <a href="https://uiwjs.github.io/react-md-editor/coverage/lcov-report" target="__blank">
-        <img alt="Coverage Status" src="https://uiwjs.github.io/react-md-editor/coverage/badges.svg" />
+        <img alt="Coverage Status" src="https://uiwjs.github.io/react-md-editor/badges.svg" />
       </a>
       <br />
       <a href="https://github.com/uiwjs/react-md-editor/actions" target="__blank">