[gtk/listmodel-get-item: 2/4] docs: Mention the GtkWidget.destroy vfunc

[Matthias Clasen <matthiasc src gnome org>]

commit ee34e1acc5bbd1eb670a38d897159247174f66dc
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Jun 11 10:11:53 2021 -0400

    docs: Mention the GtkWidget.destroy vfunc
    
    Mention GtkWidget.destroy in the migration guide.

 docs/reference/gtk/migrating-3to4.md | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/docs/reference/gtk/migrating-3to4.md b/docs/reference/gtk/migrating-3to4.md
index ff2337e18f..3779465b35 100644
--- a/docs/reference/gtk/migrating-3to4.md
+++ b/docs/reference/gtk/migrating-3to4.md
@@ -243,6 +243,10 @@ in GTK 3, you can prepare for the switch by using `gtk_widget_destroy()`
 only on toplevel windows, and replace all other uses with
 `gtk_container_remove()` or `g_object_unref()`.
 
+### Stop using the GtkWidget.destroy vfunc
+
+Instead of implementing GtkWidget.destroy, you can implement GObject.dispose.
+
 ### Reduce the use of generic container APIs
 
 GTK 4 removes `gtk_container_add()` and `gtk_container_remove()`. While there