[default-theme]add config.js, /README.md with frontmatter

reference:
- https://v1.vuepress.vuejs.org/theme/default-theme-config.html#homepage
- vuejs/vuepress#274

docs/.vuepress/config.js

@@ -0,0 +1,18 @@
+module.exports = {
+  title: "My Vuepress Docs",
+  theme: "@vuepress/theme-default",
+  themeConfig: {
+    nav: [
+      { text: 'Home', link: '/' },
+      { text: 'Guide', link: '/guide/' },
+      { text: 'External', link: 'https://google.com' },
+    ],
+    sidebar: {
+      '/': [
+        '',
+        ''
+      ],
+      '/about/': []
+    }
+  }
+}

docs/README.md

@@ -1 +1,17 @@
-# Hello VuePress
+---
+home: true
+heroImage: hero.png
+heroText: Hero Title
+tagline: Hero subtitle
+actionText: Get Started →
+actionLink: /guide/
+features:
+- title: Simplicity First
+  details: Minimal setup with markdown-centered project structure helps you focus on writing.
+- title: Vue-Powered
+  details: Enjoy the dev experience of Vue + webpack, use Vue components in markdown, and develop custom themes with Vue.
+- title: Performant
+  details: VuePress generates pre-rendered static HTML for each page, and runs as an SPA once a page is loaded.
+footer: MIT Licensed | Copyright © 2018-present Evan You
+---
+