[newlib-cygwin] Cygwin: document the recent pipe changes

[Ken Brown <kbrown@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=593a86f9b0262243510b2d9c97868a6b60f89c69

commit 593a86f9b0262243510b2d9c97868a6b60f89c69
Author: Ken Brown <kbrown@cornell.edu>
Date:   Tue Sep 14 14:59:28 2021 -0400

    Cygwin: document the recent pipe changes

Diff:
---
 winsup/cygwin/release/3.3.0 | 4 ++++
 winsup/doc/new-features.xml | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/winsup/cygwin/release/3.3.0 b/winsup/cygwin/release/3.3.0
index 0494cd5ab..b8865666e 100644
--- a/winsup/cygwin/release/3.3.0
+++ b/winsup/cygwin/release/3.3.0
@@ -23,6 +23,10 @@ What changed:
   rather than a Bnnn constant, as on Linux.
   Addresses: https://cygwin.com/pipermail/cygwin/2021-July/248887.html
 
+- The internal implementation of pipes has been overhauled; this
+  should result in improved performance.
+  Adresses: https://cygwin.com/pipermail/cygwin/2021-August/249238.html
+
 
 Bug Fixes
 ---------
diff --git a/winsup/doc/new-features.xml b/winsup/doc/new-features.xml
index ba9231a6d..6285e33bd 100644
--- a/winsup/doc/new-features.xml
+++ b/winsup/doc/new-features.xml
@@ -35,6 +35,11 @@ The speed argument to cfsetspeed(3) can now be a numerical baud rate
 rather than a Bnnn constant, as on Linux.
 </para></listitem>
 
+<listitem><para>
+The internal implementation of pipes has been overhauled; this should
+result in improved performance.
+</para></listitem>
+
 </itemizedlist>
 
 </sect2>