Prompt user to turn off JavaScript on posts page

- Credits to Heydon Pickering
  - From the talk "State of the browser 2021; Please Disable JavaScript To View This Site"

Signed-off-by: Raymonzut <me@raymon.dev>

client/templates/post_index_page.html

@@ -14,6 +14,13 @@
     media="all"
   >
   <link defer rel="stylesheet" href="/css/general.css" media="all">
+
+  <script type="text/javascript">
+    document.addEventListener('DOMContentLoaded',
+      () => document.body.textContent = 'Please disable JavaScript to view the blog posts.',
+      false);
+  </script>
+
 </head>
 <body>
   <main>