Only provide deleteToken if requested by user

assets/templates/html/index.html.tmpl

@@ -9,6 +9,9 @@ the command line.
 ## USAGE
 
     # Shorten a URL
-    curl -F'shorten=http://example.com/some/long/url' <a href="https://hashru.link">https://hashru.link</a>
+    curl -F'shorten=http://example.com/some/long/url' <a href="{{Request.Host}}">{{Request.Host}}</a>
+
+    # Shorten a URL with a token to delete it later
+    curl -F'shorten=http://example.com/some/long/url' -F'deleteToken=' <a href="{{Request.Host}}">{{Request.Host}}</a>
 </pre>
 {{end}}