README: Update to include H7 series support.

Author: dpgeorge

README.md

@@ -1,10 +1,10 @@
-STM32 Cube library - CMSIS and HAL for F4, F7 and L4 microcontrollers
-=====================================================================
+STM32 Cube library - CMSIS and HAL for F4, F7, H7 and L4 microcontrollers
+=========================================================================
 
 This repository contains a copy of STMicroelectronic's STM32 Cube firmware
-library, with CMSIS-device and HAL code for STM32F4xx, STM32F7xx and STM32L4xx
-microcontrollers.  Minor changes are applied to the HAL source to support
-MicroPython's port to the STM32.
+library, with CMSIS-device and HAL code for STM32F4xx, STM32F7xx, STM32H7xx
+and STM32L4xx 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