Document recent FIFO changes

winsup/cygwin/release/3.1.5

@@ -3,6 +3,8 @@ What changed:
 
 - Support WSL symlinks.  Create those by default now.
 
+- FIFOs can now be opened multiple times for reading.
+
 
 Bug Fixes:
 ----------
@@ -22,3 +24,7 @@ Bug Fixes:
 - Fix error handling in raw disk writes and allow full disk writes
   including necessary locking on floppies as well.
   Addresses: https://cygwin.com/pipermail/cygwin/2020-April/244610.html
+
+- Fix several FIFO bugs.
+  Addresses: https://sourceware.org/pipermail/cygwin/2020-March/000206.html
+             https://sourceware.org/pipermail/cygwin/2020-April/244518.html

winsup/doc/new-features.xml

@@ -86,6 +86,10 @@ https://gitlab.freedesktop.org/terminal-wg/specifications/issues/9.
 Support WSL symlinks.  Create those by default now.
 </para></listitem>
 
+<listitem><para>
+FIFOs can now be opened multiple times for reading.
+</para></listitem>
+
 </itemizedlist>
 
 </sect2>