migration-guide: 4.4: add entry about STM32 power configuration

Signed-off-by: Mathieu Choplain <mathieu.choplain-ext@st.com>

Author: mathieuchopstm

doc/releases/migration-guide-4.4.rst

@@ -32,6 +32,29 @@ Boards
 Device Drivers and Devicetree
 *****************************
 
+* STM32 power supply configuration is now performed using Devicetree properties.
+  New bindings :dtcompatible:`st,stm32h7-pwr`, :dtcompatible:`st,stm32h7rs-pwr`
+  and :dtcompatible:`st,stm32-dualreg-pwr` have been introduced, and all Kconfig
+  symbols related to power supply configuration have been removed:
+
+  * ``CONFIG_POWER_SUPPLY_LDO``
+
+  * ``CONFIG_POWER_SUPPLY_DIRECT_SMPS``,
+
+  * ``CONFIG_POWER_SUPPLY_SMPS_1V8_SUPPLIES_LDO``
+
+  * ``CONFIG_POWER_SUPPLY_SMPS_2V5_SUPPLIES_LDO``,
+
+  * ``CONFIG_POWER_SUPPLY_SMPS_1V8_SUPPLIES_EXT_AND_LDO``
+
+  * ``CONFIG_POWER_SUPPLY_SMPS_2V5_SUPPLIES_EXT_AND_LDO``
+
+  * ``CONFIG_POWER_SUPPLY_SMPS_1V8_SUPPLIES_EXT``
+
+  * ``CONFIG_POWER_SUPPLY_SMPS_2V5_SUPPLIES_EXT``
+
+  * ``CONFIG_POWER_SUPPLY_EXTERNAL_SOURCE``
+
 Bluetooth
 *********