[README] Adapt code to new style

Next to every IE will download the webpage first anyways.

README.md

@@ -492,9 +492,9 @@ If you want to add support for a new site, you can follow this quick list (assum
 
         def _real_extract(self, url):
             video_id = self._match_id(url)
+            webpage = self._download_webpage(url, video_id)
 
             # TODO more code goes here, for example ...
-            webpage = self._download_webpage(url, video_id)
             title = self._html_search_regex(r'<h1>(.*?)</h1>', webpage, 'title')
 
             return {