chore: 4.12.0 release notes

Author: MohamadJaara

app/src/main/play/release-notes/en-US/default.txt

@@ -1,16 +1,9 @@
 New
-- Fresh design - completely rebuilt
-- Add Reactions to messages
-- Swipe left to reply
-- Scroll to end button
-- Navigate to original message from a reply
-- Accessible main navigation & updated conversation list with activity section
-- Improved conversation search
-- Easier 1:1 & group creation
-- Group chats have distinct colors
-- Call controls always accessible
-- Text field adjusts for longer messages
+- Channels
+- Simplified login flow
 
-Improved
-- Reliable notifications
-- Better visual contrast (WCAG 2.1 AA)
+Improvement
+- Design for files and video previews
+
+Fixes
+- Resolved several issues