[gtkmm] builder: rm accidental argument name in Return doc

[Daniel Boles <dboles src gnome org>]

commit 918228ac735fc53992c43e559a60acd192d8a74e
Author: Daniel Boles <dboles src gnome org>
Date:   Sun May 19 19:18:54 2019 +0100

    builder: rm accidental argument name in Return doc
    
    This is left over from when it was an output parameter.

 gtk/src/builder.hg | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/src/builder.hg b/gtk/src/builder.hg
index d111fe3a..ece41e3c 100644
--- a/gtk/src/builder.hg
+++ b/gtk/src/builder.hg
@@ -641,7 +641,7 @@ public:
    * @param builder The Gtk::Builder from which to get the widget.
    * @param name The name of the widget.
    * @param args Additional arguments to pass to the constructor of the derived class.
-   * @return widget A pointer to the widget, or <tt>nullptr</tt> on failure.
+   * @return A pointer to the widget, or <tt>nullptr</tt> on failure.
    *
    * @newin{3,96}
    */