[gtkmm-documentation] Fixed typo in string

[Daniel Mustieles GarcÃa <dmustieles src gnome org>]

commit 9b39b053f9c6930de4d5010c5939449a028354fd
Author: Daniel Mustieles <daniel mustieles gmail com>
Date:   Mon Mar 5 17:04:43 2012 +0100

    Fixed typo in string

 docs/tutorial/C/gtkmm-tutorial-in.xml |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/docs/tutorial/C/gtkmm-tutorial-in.xml b/docs/tutorial/C/gtkmm-tutorial-in.xml
index acf934d..53fa551 100644
--- a/docs/tutorial/C/gtkmm-tutorial-in.xml
+++ b/docs/tutorial/C/gtkmm-tutorial-in.xml
@@ -1906,7 +1906,7 @@ in &gtkmm; are descendants of <classname>Gtk::Bin</classname>, including
 Yes, that's correct: a Window can contain at most one widget. How, then, can
 we use a window for anything useful?  By placing a multiple-child container in
 the window. The most useful container widgets are
-<classname>Gtk:Grid</classname> and <classname>Gtk:Box</classname>.
+<classname>Gtk::Grid</classname> and <classname>Gtk::Box</classname>.
 </para>