docs: release notes: Mention GNSS periodic config APIs removed

Mention that the GNSS periodic config APIs have been removed in the
release notes for 4.0

Signed-off-by: Bjarki Arge Andreasen <[email protected]>

Author: bjarki-andreasen

doc/releases/migration-guide-4.0.rst

@@ -97,9 +97,12 @@ Enhanced Serial Peripheral Interface (eSPI)
 GNSS
 ====
 
- * The u-blox M10 driver has been renamed to M8 as it only supports M8 based devices.
-   Existing devicetree compatibles should be updated to :dtcompatible:`u-blox,m8`, and Kconfig
-   symbols swapped to :kconfig:option:`CONFIG_GNSS_U_BLOX_M8`.
+* The u-blox M10 driver has been renamed to M8 as it only supports M8 based devices.
+  Existing devicetree compatibles should be updated to :dtcompatible:`u-blox,m8`, and Kconfig
+  symbols swapped to :kconfig:option:`CONFIG_GNSS_U_BLOX_M8`.
+
+* The APIs :c:func:`gnss_set_periodic_config` and :c:func:`gnss_get_periodic_config` have
+  been removed. (:github:`76392`)
 
 Input
 =====