[gtk+] docs: Improve grammar in GtkHeaderBar overview

[Murray Cumming <murrayc src gnome org>]

commit a2208712505ed94c53c78a874a7a75a06be6c01a
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Jan 31 11:24:18 2014 +0100

    docs: Improve grammar in GtkHeaderBar overview

 gtk/gtkheaderbar.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkheaderbar.c b/gtk/gtkheaderbar.c
index 36c7e70..a1769f4 100644
--- a/gtk/gtkheaderbar.c
+++ b/gtk/gtkheaderbar.c
@@ -37,8 +37,8 @@
  * @Title: GtkHeaderBar
  * @See_also: #GtkBox, #GtkActionBar
  *
- * GtkHeaderBar is similar to a horizontal #GtkBox, it allows to place
- * children at the start or the end. In addition, it allows a title and
+ * GtkHeaderBar is similar to a horizontal #GtkBox. It allows children to 
+ * be placed at the start or the end. In addition, it allows a title and
  * subtitle to be displayed. The title will be centered with respect to
  * the width of the box, even if the children at either side take up
  * different amounts of space. The height of the titlebar will be