feat(element demo): 移除内置的 elementUI demo

src/views/demo/element/index.vue

@@ -0,0 +1,19 @@
+<template>
+  <d2-container type="ghost">
+    <d2-module-index-banner slot="header" v-bind="banner"/>
+  </d2-container>
+</template>
+
+<script>
+export default {
+  data () {
+    return {
+      banner: {
+        title: 'ElementUI',
+        subTitle: 'D2Admin 集成由饿了么出品的 ElementUI',
+        link: 'http://element.eleme.io'
+      }
+    }
+  }
+}
+</script>