chore: add the ICU independent language detection to the changelog

Opens the 2.1.2 section, the locale_accept_from_http() shortcut from
2ac4004f was released in 2.1.1.

CHANGELOG.md

@@ -1,5 +1,8 @@
 # PrivateBin version history
 
+## 2.1.2 (not yet released)
+* FIXED: Browser language detection no longer depends on the ICU library, which could pick Simplified instead of Traditional Chinese or skip Corsican, Latin and Lojban (#2078)
+
 ## 2.1.1 (2026-11-04)
 * ADDED: Translation for Korean (#2071)
 * ADDED: Comments authenticate the IDs of their document and parent comment if present. Older comments without these IDs are still accepted and shown, unless the new `discussionrequireauthenticatedids` option is enabled to validate these fields (#2101)