Add ChangeLog entry for #3239: win2k net support

Signed-off-by: Janos Follath <janos.follath@arm.com>
diff --git a/ChangeLog.d/add_win2k_net_socket.txt b/ChangeLog.d/add_win2k_net_socket.txt
new file mode 100644
index 0000000..9842c5d
--- /dev/null
+++ b/ChangeLog.d/add_win2k_net_socket.txt
@@ -0,0 +1,2 @@
+Features
+   * Add support for Windows 2000 in net_sockets. Contributed by opatomic. #3239