Update URL for documentation.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

Doxyfile

@@ -998,25 +998,25 @@ QCH_FILE               =
 
 # The QHP_NAMESPACE tag specifies the namespace to use when generating 
 # Qt Help Project output. For more information please see 
-# http://doc.trolltech.com/qthelpproject.html#namespace
+# http://doc.qt.io/qt-5/qthelpproject.html#namespace
 
 QHP_NAMESPACE          = org.doxygen.Project
 
 # The QHP_VIRTUAL_FOLDER tag specifies the namespace to use when generating 
 # Qt Help Project output. For more information please see 
-# http://doc.trolltech.com/qthelpproject.html#virtual-folders
+# http://doc.qt.io/qt-5/qthelpproject.html#virtual-folders
 
 QHP_VIRTUAL_FOLDER     = doc
 
 # If QHP_CUST_FILTER_NAME is set, it specifies the name of a custom filter to 
 # add. For more information please see 
-# http://doc.trolltech.com/qthelpproject.html#custom-filters
+# http://doc.qt.io/qt-5/qthelpproject.html#custom-filters
 
 QHP_CUST_FILTER_NAME   = 
 
 # The QHP_CUST_FILT_ATTRS tag specifies the list of the attributes of the 
 # custom filter to add. For more information please see 
-# <a href="http://doc.trolltech.com/qthelpproject.html#custom-filters"> 
+# <a href="http://doc.qt.io/qt-5/qthelpproject.html#custom-filters">
 # Qt Help Project / Custom Filters</a>.
 
 QHP_CUST_FILTER_ATTRS  = 
@@ -1024,7 +1024,7 @@ QHP_CUST_FILTER_ATTRS  =
 # The QHP_SECT_FILTER_ATTRS tag specifies the list of the attributes this 
 # project's 
 # filter section matches. 
-# <a href="http://doc.trolltech.com/qthelpproject.html#filter-attributes"> 
+# <a href="http://doc.qt.io/qt-5/qthelpproject.html#filter-attributes">
 # Qt Help Project / Filter Attributes</a>.
 
 QHP_SECT_FILTER_ATTRS  =