update changelog

Author: adbenitez

CHANGELOG.md

@@ -13,6 +13,7 @@
 * warn if the app has not been updated after 6 months instead of 1 year
 * avoid "unknown sender for this chat" error
 * properly display "Messages are end-to-end encrypted." in all encrypted groups
+* show dialog if user has permanently denied camera permission and tries to take picture for group avatar
 * several small fixes and improvements
 * update to core 2.17.0