doc: releases: add working draft release notes + guide for v4.0.0

Add working drafts for the release notes and migration guide for v4.0.0

(cherry picked from commit f09ea47)

Original-Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>
GitOrigin-RevId: f09ea47
Change-Id: I80360d160f7e5f38178b8fac4ae1d7cd2a221dec
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5746385
Tested-by: Fabio Baltieri <fabiobaltieri@google.com>
Commit-Queue: Fabio Baltieri <fabiobaltieri@google.com>
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Reviewed-by: Fabio Baltieri <fabiobaltieri@google.com>

doc/releases/index.rst

@@ -86,6 +86,7 @@ needs to be changed are to be detailed in the release's migration guide.
    eol_releases
    release-notes-2.7
    release-notes-3.[5-7]
+   release-notes-4.0
 
 Migration Guides
 ****************

doc/releases/migration-guide-4.0.rst

@@ -0,0 +1,112 @@
+:orphan:
+
+.. _migration_4.0:
+
+Migration guide to Zephyr v4.0.0 (Working Draft)
+################################################
+
+This document describes the changes required when migrating your application from Zephyr v3.7.0 to
+Zephyr v4.0.0.
+
+Any other changes (not directly related to migrating applications) can be found in
+the :ref:`release notes<zephyr_4.0>`.
+
+.. contents::
+    :local:
+    :depth: 2
+
+Build System
+************
+
+Kernel
+******
+
+Boards
+******
+
+Modules
+*******
+
+Mbed TLS
+========
+
+Trusted Firmware-M
+==================
+
+LVGL
+====
+
+Device Drivers and Devicetree
+*****************************
+
+Controller Area Network (CAN)
+=============================
+
+Display
+=======
+
+Enhanced Serial Peripheral Interface (eSPI)
+===========================================
+
+GNSS
+====
+
+Input
+=====
+
+Interrupt Controller
+====================
+
+LED Strip
+=========
+
+Sensors
+=======
+
+Serial
+======
+
+Regulator
+=========
+
+Bluetooth
+*********
+
+Bluetooth HCI
+=============
+
+Bluetooth Mesh
+==============
+
+Bluetooth Audio
+===============
+
+Bluetooth Classic
+=================
+
+Bluetooth Host
+==============
+
+Bluetooth Crypto
+================
+
+Networking
+**********
+
+Other Subsystems
+****************
+
+Flash map
+=========
+
+hawkBit
+=======
+
+MCUmgr
+======
+
+Modem
+=====
+
+Architectures
+*************