Correct example code (#3408)

The code as written did not work.  I was looking for a terse script to display some local html content, so i googled "node server static".  Although this article is only the 5th result, it should be suitable for copy-paste turnkey.

The article could use some other modernization as well, but I'll leave that out to avoid muddying the main point.

locale/en/knowledge/HTTP/servers/how-to-serve-static-files.md

@@ -36,7 +36,7 @@ There is a good static file server called [node-static](https://github.com/cloud
 var static = require('node-static');
 var http = require('http');
 
-var file = new(static.Server)();
+var file = new(static.Server)(__dirname);
 
 http.createServer(function (req, res) {
   file.serve(req, res);