Cygwin: Add release note for recent pty related fixes

Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>

Author: tyan0

winsup/cygwin/release/3.6.6

@@ -17,3 +17,10 @@ Fixes:
 
 - Improve newgrp(1) POSIX compatibility and its documentation.
   Addresses: https://cygwin.com/pipermail/cygwin/2025-December/259055.html
+
+- Fix ESC sequence parsing in pty_master_fwd_thread.
+
+- Add a new workaround which prevent the screen from being garbled when
+  cmd.exe is started using rlwrap in Win11.
+
+- Fix a bug where app execution aliases no longer start correctly.