message: refactor(examples): adjust meta tags
diff: <meta charset="utf-8" />
  <link rel="icon" href="%PUBLIC_URL%/favicon.ico" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  - <meta name="theme-color" content="#000000" />
  - <meta
  - name="description"
  - content="Web site created using create-react-app"
  - />
  - <link rel="apple-touch-icon" href="logo192.png" />
  - <!--
  - manifest.json provides metadata used when your web app is installed on a
  - user's mobile device or desktop. See https://developers.google.com/web/fundamentals/web-app-manifest/
  - -->
  - <link rel="manifest" href="%PUBLIC_URL%/manifest.json" />
  - <!--
  - Notice the use of %PUBLIC_URL% in the tags above.
  - It will be replaced with the URL of the `public` folder during the build.
  - Only files inside the `public` folder can be referenced from the HTML.
  -
  - Unlike "/favicon.ico" or "favicon.ico", "%PUBLIC_URL%/favicon.ico" will
  - work correctly both with client-side routing and a non-root public URL.
  - Learn how to configure a non-root public URL by running `npm run build`.
  - -->
  - <title>React App</title>
  + <meta name="theme-color" content="#222222" />
  + <meta name="description" content="react flow examples" />
  + <title>React Flow Examples</title>
  </head>
  <body>
  <noscript>You need to enable JavaScript to run this app.</noscript>
  <div id="root"></div>
  - <!--
  - This HTML file is a template.
  - If you open it directly in the browser, you will see an empty page.
  -
  - You can add webfonts, meta tags, or analytics to this file.
  - The build step will place the bundled scripts into the <body> tag.
  -
  - To begin the development, run `npm start` or `yarn start`.
  - To create a production bundle, use `npm run build` or `yarn build`.
  - -->
  </body>
  </html>
  