link broken in documentation on-line

[acerion <acerion ps pl>]

Hello

I was browsing your on-line documentation, and came accross broken link:
page:  
http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/ch03s04.html  
(Glib::ustring). There is a link named "Reference".
pointing to  
http://www.gtkmm.org/docs/gtkmm-2.4/docs/reference/html/classGlib_1_1ustring.html,  
which is broken.

Kamil