Merge pull request #474 from tropicsquare/ETR01SDK-568-Add-HAL-for-STM32U5xx-documentation

ETR01SDK-568: Add STM32U5xx HAL documentation

Author: medexs

docs/compatibility/host_platforms/stm32.md

@@ -4,6 +4,8 @@ Currently supported STM32 platforms are:
 - NUCLEO-F439ZI
 - NUCLEO-L432KC
     - Using interrupt pin (`LT_USE_INT_PIN`) is not supported for this platform.
+- STM32U5xx series MCUs, tested with:
+    - NUCLEO-U545RE-Q
 
 HALs for these ports are available in the `libtropic/hal/stm32/` directory.