update changelog for reply-to strikethrough

CHANGELOG.md

@@ -19,6 +19,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Autocomplete domains from list of known instances
 - 'Bot' settings option and badge
 - Added profile meta data fields that can be set in profile settings
+- When a post is a reply to an unavailable post, the 'Reply to'-text has a strike-through style
 
 ### Changed
 - Registration page no longer requires email if the server is configured not to require it