[libadwaita/wip/exalm/avatar-paintable: 11/12] doc: Mention avatar changes in the migration guide

[Alexander Mikhaylenko <alexm src gnome org>]

commit a133c1dfc45a673a82563ef2417bf1ee020b464b
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Tue May 25 14:45:56 2021 +0500

    doc: Mention avatar changes in the migration guide

 doc/migrating-libhandy-1-4-to-libadwaita.md | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/doc/migrating-libhandy-1-4-to-libadwaita.md b/doc/migrating-libhandy-1-4-to-libadwaita.md
index 1d4198bb..d801159e 100644
--- a/doc/migrating-libhandy-1-4-to-libadwaita.md
+++ b/doc/migrating-libhandy-1-4-to-libadwaita.md
@@ -227,6 +227,11 @@ page objects, similarly to [class@Gtk.Stack]. For example,
 [method@Adw.SqueezerPage.set_enabled] should be used to replace
 `hdy_squeezer_set_child_enabled()`.
 
+### Adapt to [class@Adw.Avatar] API Changes
+
+The `HdyAvatar:loadable-icon` property has been removed along with its getter
+and setter. It can be replaced by [property@Adw.Avatar:custom-image].
+
 ### Adapt to Stylesheet Changes
 
 Most widgets don't have a backdrop state anymore, and the following public