chore: add google search meta

Author: QingWei-Li

docs/index.html

@@ -4,6 +4,7 @@
   <meta charset="UTF-8">
   <title>docsify</title>
   <link rel="icon" href="_media/favicon.ico">
+  <meta name="google-site-verification" content="6t0LoIeFksrjF4c9sqUEsVXiQNxLp2hgoqo0KryT-sE" />
   <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
   <meta name="keywords" content="doc,docs,documentation,gitbook,creator,generator,github,jekyll,github-pages">
   <meta name="description" content="A magical documentation generator.">