[gtk] docs: Fix build

[Benjamin Otte <otte src gnome org>]

commit 7a3ffec76224ec51a4df1c7c12d81e89a4ee1694
Author: Benjamin Otte <otte redhat com>
Date:   Thu May 30 18:26:32 2019 +0200

    docs: Fix build

 docs/reference/gtk/migrating-3to4.xml | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/docs/reference/gtk/migrating-3to4.xml b/docs/reference/gtk/migrating-3to4.xml
index 0cdda924d2..39a52e1f21 100644
--- a/docs/reference/gtk/migrating-3to4.xml
+++ b/docs/reference/gtk/migrating-3to4.xml
@@ -802,6 +802,7 @@
         Use GTK_IS_ROOT, GTK_IS_NATIVE or GTK_IS_WINDOW
         instead, as appropriate.
       </para>
+    </section>
 
     <section>
       <title>gtk_widget_get_toplevel has been removed</title>
@@ -810,6 +811,8 @@
         Use gtk_widget_get_root() or gtk_widget_get_native()
         instead, as appropriate.
       </para>
+    </section>
+
   </section>
 
 </chapter>