Remove errant manifest mention

index.html

@@ -5,7 +5,6 @@
     <title>Lexy's Labyrinth</title>
     <link rel="stylesheet" type="text/css" href="style.css">
     <link rel="shortcut icon" type="image/png" href="icon.png">
-    <link rel="manifest" type="application/json" href="manifest.json">
     <script>
         "use strict";
         {