README: Update to include U5 series support.

Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

README.md

@@ -1,11 +1,11 @@
-STM32 Cube library - CMSIS and HAL for F0, F4, F7, G0, G4, H5, H7, L0, L1, L4, N6, WB and WL microcontrollers
-=============================================================================================================
+STM32 Cube library - CMSIS and HAL for F0, F4, F7, G0, G4, H5, H7, L0, L1, L4, N6, U5, WB and WL microcontrollers
+=================================================================================================================
 
 This repository contains a copy of STMicroelectronic's STM32 Cube firmware
 library, with CMSIS-device and HAL code for STM32F0xx, STM32F4xx, STM32F7xx,
 STM32G0xx, STM32G4xx, STM32H5xx, STM32H7xx, STM32L0xx, STM32L1xx, STM32L4xx,
-STM32N6xx, STM32WBxx and STM32WLxx microcontrollers.  Minor changes are
-applied to the HAL source to support MicroPython's port to the STM32.
+STM32N6xx, STM32U5xx, STM32WBxx and STM32WLxx microcontrollers.  Minor changes
+are applied to the HAL source to support MicroPython's port to the STM32.
 
 The "vendor" branch contains the original sources and is updated from
 time-to-time when new versions become available.  The upstream sources are