improve demo component

src/main.js

@@ -1,18 +1,16 @@
 // This is the main.js file. Import global CSS and scripts here.
 // The Client API can be used here. Learn more: gridsome.org/docs/client-api
 
+import Prism from 'prismjs'
 import 'prismjs/themes/prism-okaidia.css'
 
 import DefaultLayout from '~/layouts/Default.vue'
-
-import Prism from 'prismjs'
-
+import Demo from '~/components/Demo.vue'
 
 export default function (Vue, { router, head, isClient }) {
-
+  Vue.component('Layout', DefaultLayout)
+  Vue.component('Demo', Demo)
   Vue.filter('highlight', (code, lang = 'javascript') => {
     return Prism.highlight(code, Prism.languages[lang], lang)
   })
-
-  Vue.component('Layout', DefaultLayout)
 }