[libadwaita/wip/exalm/outline-list-button] doc: .outline -> .list-button

[Alexander Mikhaylenko <alexm src gnome org>]

commit 264d7a91734017388e29abdb15aac41e91709a7f
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Wed Nov 24 05:32:53 2021 +0500

    doc: .outline -> .list-button
    
    First we renamed it, then removed it. No need to mention the temporary
    name.

 doc/migrating-libhandy-1-4-to-libadwaita.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/doc/migrating-libhandy-1-4-to-libadwaita.md b/doc/migrating-libhandy-1-4-to-libadwaita.md
index e746406f..2539260c 100644
--- a/doc/migrating-libhandy-1-4-to-libadwaita.md
+++ b/doc/migrating-libhandy-1-4-to-libadwaita.md
@@ -401,7 +401,7 @@ The `.combo` popover style class has been removed. Use `.menu` instead. You may
 need to remove manually added margins, padding or minimum height from the list
 items inside while doing it.
 
-### Adapt to the `button.outline` style removal
+### Adapt to the `button.list-button` style removal
 
 The `.list-button` style class has been removed with no replacement. The regular
 button style should be used instead.