docs: update doc

Author: tangjinzhou

site/components/GoogleAds.vue

@@ -19,7 +19,7 @@ export default {
   },
   render() {
     return (
-      <div class="google-ads">
+      <div class="google-ads" id="api">
         <ins
           ref="ins"
           class="adsbygoogle"

site/components/layout.vue

@@ -131,9 +131,11 @@ export default {
         const title = isCN ? cnTitle : usTitle;
         lis.push(<a-anchor-link key={id} href={`#${id}`} title={title} />);
       });
+      const showApi = this.$route.path.indexOf('/components/') !== -1;
       return (
         <a-anchor offsetTop={100} class="demo-anchor">
           {lis}
+          {showApi ? <a-anchor-link key="API" title="API" href="#api" /> : ''}
         </a-anchor>
       );
     },