Cygwin: Update the 3.6.11 release notes regarding recent bug fixes

(cherry picked from commit 230404cef9)

winsup/cygwin/release/3.6.11

@@ -3,3 +3,24 @@ Fixes:
 
 - Fix a deadlock in fifo open, that is a regression caused in 3.6.10
   Addresses: https://cygwin.com/pipermail/cygwin/2026-July/259884.html
+
+- Fix a regression of console input where the input would be lost.
+  Addresses: https://cygwin.com/pipermail/cygwin/2026-August/259915.html
+
+- Fix the crash that occurs when getlocalename_l() is called for "C"
+  locale.
+  Addresses: https://cygwin.com/pipermail/cygwin/2026-August/259965.html
+
+- Fix a bug in calculation of loadavg.
+
+- Provide correct number of the threads in /proc/<pid>/stat and
+  /proc/<pid>/status.
+
+- Fix a regression of clipboard in Windows 10.
+  Addresses: https://cygwin.com/pipermail/cygwin/2026-September/260058.html
+
+- Fix a hang of the console process that occurs when the master_thread is
+  terminated early.
+  Addresses: https://cygwin.com/pipermail/cygwin/2026-September/260037.html
+
+- Fix a few more historical console bugs.