[glibmm] extraclassinit: Fix typo in comment in doc example

[Daniel Boles <dboles src gnome org>]

commit b256e44a694490c7a0784da28464d7c9e78d112f
Author: Daniel Boles <dboles src gnome org>
Date:   Sun Dec 9 23:31:19 2018 +0000

    extraclassinit: Fix typo in comment in doc example

 glib/glibmm/extraclassinit.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/glib/glibmm/extraclassinit.h b/glib/glibmm/extraclassinit.h
index 22a0e822..29c2a952 100644
--- a/glib/glibmm/extraclassinit.h
+++ b/glib/glibmm/extraclassinit.h
@@ -58,7 +58,7 @@ namespace Glib
  * public:
  *   MyWidget()
  *   :
- *   // The GType name will be gtkmm__CustomObject_MyMidget
+ *   // The GType name will be gtkmm__CustomObject_MyWidget
  *   Glib::ObjectBase("MyWidget"), // Unique class name
  *   MyExtraInit("my-widget"),
  *   Gtk::Widget()