tour: update index template favicon url

Current favicon link is broken and returns 404. Fixes
`href="/static/img/favicon.ico"` to become `href="/favicon.ico"`.

Change-Id: I37ad0e6be8f4d4cdc9245fcd122fab56f7fb3eaa
Reviewed-on: https://go-review.googlesource.com/23632
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/template/index.tmpl b/template/index.tmpl
index 84cbe30..01f94b4 100755
--- a/template/index.tmpl
+++ b/template/index.tmpl
@@ -7,7 +7,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no">
     <meta name="apple-mobile-web-app-capable" content="yes">
     <meta name="mobile-web-app-capable" content="yes">
-    <link rel="shortcut icon" sizes="196x196" href="/static/img/favicon.ico">
+    <link rel="shortcut icon" sizes="196x196" href="/favicon.ico">
     <link rel="stylesheet" href="/static/css/app.css" />
     <link rel="stylesheet" href="/static/lib/codemirror/lib/codemirror.css">
     <link href='//fonts.googleapis.com/css?family=Inconsolata' rel='stylesheet' type='text/css'>