doc: update changelog for anonymized handling

CHANGELOG.md

@@ -8,6 +8,13 @@ have notable changes.
 
 Changes since v2.33
 
+### Additions
+- Workflow has new feature, anonymized handling:
+  - Anonymized handling can be turned on in workflow admin UI.
+  - When enabled, applicants and members can no longer see handler PII data in application UI or API.
+  - In events, attachments, and emails, anonymized handler name is replaced with customizable translation key `:t.roles/anonymous-handler`, which defaults to `:t.roles/handler`.
+  - In API, handler `:userid` attribute is replaced with `:handler` keyword.
+
 ### Fixes
 - Email template parameters for `:application-expiration-notification` event are now documented. The parameters are different from standard event email parameters, which may have caused confusion.