Fix crucial typo in script-escaping example

Author: mathiasbynens

source

@@ -58586,7 +58586,7 @@ console.log(example);</pre>
    avoided entirely:</p>
 
    <pre>&lt;script><mark>
-  var example = 'Consider this string: &lt;\!-- &lt;\script>';
+  var example = 'Consider this string: &lt;\!-- &lt;\/script>';
   console.log(example);
 </mark>&lt;/script>
 &lt;!-- this is just a comment between script blocks -->