[newlib-cygwin/cygwin-3_5-branch] Cygwin: Document hang fixs introduced in 3.5.5

[Takashi Yano]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=b838c8d21ab4018daad23520190cc4ecd001e3be

commit b838c8d21ab4018daad23520190cc4ecd001e3be
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Mon Jan 20 13:52:10 2025 +0900

    Cygwin: Document hang fixs introduced in 3.5.5
    
    Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>

Diff:
---
 winsup/cygwin/release/3.5.6 | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/winsup/cygwin/release/3.5.6 b/winsup/cygwin/release/3.5.6
index 19a27d326..fb1928c87 100644
--- a/winsup/cygwin/release/3.5.6
+++ b/winsup/cygwin/release/3.5.6
@@ -10,3 +10,9 @@ Fixes:
 
 - Add fd validation where needed in mq_* functions.
   Addresses: https://cygwin.com/pipermail/cygwin/2025-January/257090.html
+
+- Fix regression in 3.5.5 which causes process hangs.
+  Addresses: https://cygwin.com/pipermail/cygwin/2024-December/256954.html
+  Addresses: https://cygwin.com/pipermail/cygwin/2024-December/256971.html
+  Addresses: https://cygwin.com/pipermail/cygwin/2025-January/257058.html
+  Addresses: https://cygwin.com/pipermail/cygwin/2024-December/256987.html