Fix demo to run as memory only

docs/.vuepress/config.js

@@ -3,12 +3,15 @@ module.exports = {
   description: 'Get an instant GraphQL API for your Rails apps.',
 
   themeConfig: {
-    logo: '/hero.png',
+    logo: '/logo.png',
     nav: [
       { text: 'Guide', link: '/guide' },
       { text: 'Install', link: '/install' },
       { text: 'Github', link: 'https://github.com/dosco/super-graph' },
       { text: 'Docker', link: 'https://hub.docker.com/r/dosco/super-graph/builds' },
-    ]
+    ],
+    serviceWorker: {
+      updatePopup: true
+    }
   }
 }