[gtkmm] Fix tiny docs typo.

[Murray Cumming <murrayc src gnome org>]

commit a2e6b429629b3ea8c377145ee8b81adfba8e97e6
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Aug 30 23:41:41 2012 +0200

    Fix tiny docs typo.

 gtk/src/volumebutton.hg |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/volumebutton.hg b/gtk/src/volumebutton.hg
index 96a25e5..62dae3e 100644
--- a/gtk/src/volumebutton.hg
+++ b/gtk/src/volumebutton.hg
@@ -41,7 +41,7 @@ class VolumeButton : public ScaleButton
   _CLASS_GTKOBJECT(VolumeButton, GtkVolumeButton, GTK_VOLUME_BUTTON, Gtk::ScaleButton, GtkScaleButton)
 public:
 
-  /** Creates a olumeButton, with a range between 0 and 100, with
+  /** Creates a VolumeButton, with a range between 0 and 100, with
    * a stepping of 2. Volume values can be obtained and modified using
    * the methods from the ScaleButton base class.
    */