build: add files of vant-cli 2

packages/vant-cli/site/mobile/components/DemoNav.vue

@@ -0,0 +1,58 @@
+<template>
+  <div v-show="title" class="van-doc-demo-nav">
+    <div class="van-doc-demo-nav__title">{{ title }}</div>
+    <svg class="van-doc-demo-nav__back" viewBox="0 0 1000 1000" @click="onBack">
+      <path fill="#969799" fill-rule="evenodd" :d="path" />
+    </svg>
+  </div>
+</template>
+
+<script>
+/* eslint-disable max-len */
+export default {
+  data() {
+    return {
+      path:
+        'M296.114 508.035c-3.22-13.597.473-28.499 11.079-39.105l333.912-333.912c16.271-16.272 42.653-16.272 58.925 0s16.272 42.654 0 58.926L395.504 498.47l304.574 304.574c16.272 16.272 16.272 42.654 0 58.926s-42.654 16.272-58.926 0L307.241 528.058a41.472 41.472 0 0 1-11.127-20.023z'
+    };
+  },
+
+  computed: {
+    title() {
+      const { name } = this.$route.meta || {};
+      return name ? name.replace(/-/g, '') : '';
+    }
+  },
+
+  methods: {
+    onBack() {
+      history.back();
+    }
+  }
+};
+</script>
+
+<style lang="less">
+.van-doc-demo-nav {
+  position: relative;
+  height: 56px;
+  line-height: 56px;
+  text-align: center;
+  background-color: #fff;
+
+  &__title {
+    font-weight: 500;
+    font-size: 17px;
+    text-transform: capitalize;
+  }
+
+  &__back {
+    position: absolute;
+    top: 16px;
+    left: 16px;
+    width: 24px;
+    height: 24px;
+    cursor: pointer;
+  }
+}
+</style>