Doc: Marked the QUrlInfo class documentation as \internal

Change-Id: Ib84c9ffc181edf17850d5334c95c035428d31b6c
Reviewed-by: Qt Doc Bot <qt_docbot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/network/kernel/qurlinfo.cpp

@@ -84,6 +84,7 @@ public:
     \class QUrlInfo
     \brief The QUrlInfo class stores information about URLs.
 
+    \internal
     \ingroup io
     \ingroup network
     \inmodule QtNetwork