[libadwaita/wip/exalm/avatar-pixbuf-docs] doc: Mention hdy_avatar_draw_to_pixbuf_async() in migration guide

[Alexander Mikhaylenko <alexm src gnome org>]

commit a8bf80675c77afde451f2b54cb5649d73c2b8d33
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Thu May 27 15:46:42 2021 +0500

    doc: Mention hdy_avatar_draw_to_pixbuf_async() in migration guide

 doc/migrating-libhandy-1-4-to-libadwaita.md | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/doc/migrating-libhandy-1-4-to-libadwaita.md b/doc/migrating-libhandy-1-4-to-libadwaita.md
index d801159e..0d3e58de 100644
--- a/doc/migrating-libhandy-1-4-to-libadwaita.md
+++ b/doc/migrating-libhandy-1-4-to-libadwaita.md
@@ -232,6 +232,9 @@ page objects, similarly to [class@Gtk.Stack]. For example,
 The `HdyAvatar:loadable-icon` property has been removed along with its getter
 and setter. It can be replaced by [property@Adw.Avatar:custom-image].
 
+The `hdy_avatar_draw_to_pixbuf_async()` function has been removed, use the
+regular [method@Adw.Avatar.draw_to_pixbuf] instead.
+
 ### Adapt to Stylesheet Changes
 
 Most widgets don't have a backdrop state anymore, and the following public