doc: release: finalize release notes and migration guide

Drop the "working draft" suffix from the release notes and migration
guide page titles for 4.1.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>

Author: fabiobaltieri

doc/releases/migration-guide-4.1.rst

@@ -7,8 +7,8 @@
 
 .. _migration_4.1:
 
-Migration guide to Zephyr v4.1.0 (Working Draft)
-################################################
+Migration guide to Zephyr v4.1.0
+################################
 
 This document describes the changes required when migrating your application from Zephyr v4.0.0 to
 Zephyr v4.1.0.

doc/releases/release-notes-4.1.rst

@@ -26,8 +26,8 @@
 
 .. _zephyr_4.1:
 
-Zephyr 4.1.0 (Working Draft)
-############################
+Zephyr 4.1.0
+############
 
 We are pleased to announce the release of Zephyr version 4.1.0.
 Major enhancements with this release include: