config: disable prev/next buttons entirely

They don't work the way our guide does. Our guide, for a lack of a
better word, interleaves between paths, so the next button is almost
always incorrect.

We have always added a button to the correct next page manually anyway,
so just rely on that.

docs/.vitepress/config.mjs

@@ -15,6 +15,10 @@ export default defineConfig({
   description: "Switch CFW Guide.",
   head: [['link', { rel: 'icon', href: '/img/favicon.ico' }]],
   themeConfig: {
+    docFooter: {
+      prev: false,
+      next: false
+    },
     socialLinks: [
       { icon: 'discord', link: 'https://discord.gg/C29hYvh' },
       { icon: 'github', link: 'https://github.com/nh-server/switch-guide' }