Fix: Normalize manifest path to relative

Author: chaxus

index.html

@@ -6,7 +6,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
   <link href="img/64.png" rel="shortcut icon" />
   <link rel="icon" type="image/png" href="img/64.png" />
-  <link rel="manifest" href="./manifest.json" />
+  <link rel="manifest" href="manifest.json" />
   <meta name="theme-color" content="#0052cc" />
   <meta name="mobile-web-app-capable" content="yes" />
   <meta name="apple-mobile-web-app-status-bar-style" content="black" />