docs(example): fix hljs

example/helper/highlight-code.vue

@@ -0,0 +1,50 @@
+<template>
+  <pre class="highlight-code">
+    <code ref="code">{{value}}</code>
+  </pre>
+</template>
+
+<script>
+/* eslint-disable import/no-extraneous-dependencies */
+import hljs from 'highlight.js/lib/highlight';
+import javascript from 'highlight.js/lib/languages/javascript';
+import xml from 'highlight.js/lib/languages/xml';
+import 'highlight.js/styles/atom-one-light.css';
+
+hljs.registerLanguage('javascript', javascript);
+hljs.registerLanguage('xml', xml);
+
+export default {
+  props: {
+    value: {
+      type: String,
+    },
+  },
+  mounted() {
+    hljs.highlightBlock(this.$refs.code);
+  },
+};
+</script>
+
+<style lang="scss">
+.highlight-code {
+  margin: 0;
+  background: #fff;
+  &::after,
+  &::before {
+    width: 0;
+  }
+  // 添加优先级, 覆盖 引入的样式
+  code {
+    display: block;
+    background: #fff;
+    color: #314659;
+    line-height: 2;
+    border: 0;
+    box-shadow: none;
+    padding: 16px 32px;
+    border-radius: 2px;
+    font-size: 14px;
+  }
+}
+</style>