Cygwin: document proc fd changes

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/release/2.12.0

@@ -33,6 +33,9 @@ What changed:
   Deleting an in-use file now actually removes the file, rather than moving
   it to the recycler bin.
 
+- open(..., O_TMPFILE) now moves the file to the trash bin immediately,
+  to free the parent directory.
+
 
 Bug Fixes
 ---------
@@ -44,3 +47,8 @@ Bug Fixes
   Addresses: https://cygwin.com/ml/cygwin/2018-11/msg00171.html
 
 - Fix a bug in recognizing remote FAT/FAT32/exFAT correctly.
+
+- Allow open(2)/stat(2)/linkat(2) of a file via /proc/PID/fd/DESCRIPTOR
+  even if file has been deleted.
+  Addresses: https://cygwin.com/ml/cygwin/2018-12/msg00125.html
+             https://cygwin.com/ml/cygwin/2018-12/msg00028.html

winsup/doc/new-features.xml

@@ -52,6 +52,11 @@ Use the new POSIX unlink semantics on NTFS starting with Windows 10
 than moving it to the recycler bin.
 </para></listitem>
 
+<listitem><para>
+open(..., O_TMPFILE) now moves the file to the trash bin immediately,
+to free the parent directory.
+</para></listitem>
+
 </itemizedlist>
 
 </sect2>