docs(add sketch file): added sketch file and fixed favicon file

fix nostalgic-css#169

Author: musavvirahmed

favicon.ico

@@ -7,7 +7,9 @@
     <meta name="description" content="NES.css is a NES-style CSS Framework." />
     <meta name="keywords" content="html5,css,framework,sass,NES,8bit" />
     <meta name="author" content="© 2018 B.C.Rikko" />
-    <link rel="shortcut icon" href="favicon.ico" />
+    <link rel="shortcut icon" type="image/png" href="favicon.png">
+    <link rel="shortcut icon" sizes="196x196" href="favicon.png">
+    <link rel="apple-touch-icon" href="favicon.png">
 
     <title>NES.css - NES-style CSS Framework</title>