change W3C link to the XPath Tutorial

n1trux · n1trux · commit 31452655eb2e · 2016-03-05T13:22:56.000+01:00
the old link 404's, so I did a quick search and found the W3C XPath tutorial and replaced the link.
diff --git a/docs/scenarios/scrape.rst b/docs/scenarios/scrape.rst
@@ -49,7 +49,7 @@ will focus on the former.
 
 XPath is a way of locating information in structured documents such as
 HTML or XML documents. A good introduction to XPath is on
-`W3Schools <http://www.w3schools.com/xpath/default.asp>`_ .
+`W3Schools <http://www.w3schools.com/xsl/xpath_intro.asp>`_ .
 
 There are also various tools for obtaining the XPath of elements such as
 FireBug for Firefox or the Chrome Inspector. If you're using Chrome, you
