fix external doc references

doc/qt.index

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE QDOCINDEX>
-<INDEX url="./" title="Qt Reference Documentation" version="4.7.1">
+<INDEX url="http://qt.nokia.com/doc/4.7" title="Qt Reference Documentation" version="4.7.1">
     <namespace access="public" threadsafety="unspecified" status="commendable" name="" href="" location="" module="">
         <page access="public" status="commendable" name="3rdparty.html" href="3rdparty.html" subtype="page" title="Third-Party Licenses Used in Qt" fulltitle="Third-Party Licenses Used in Qt" subtitle="" location="3rdparty.qdoc">
             <contents name="des" title="DES ()" level="1"/>