Update README.md

Author: davetcc

README.md

@@ -114,15 +114,16 @@ There is a forum where questions can be asked, but the rules of engagement are:
 
 ### Known working and supported boards:
 
-| CPU / OS  | Boards using CPU  | Status    | Threading  |
-| --------- | ----------------- | --------- | ---------- |
-| ARM mbed  | STM32, nRF.       | Supported | CAS locking|
-| ESP8266   | Node MCU, Huzzah  | Supported | Interrupt  |
-| ESP32     | Wifi32, Huzzah32  | Supported | CAS locking|
-| SAMD ARM  | MKR, IoT, Zero.   | Supported | Interrupt  |
-| AVR       | Uno, Mega Mighty  | Supported | Interrupt  |
-| nRF52840  | Nano BLE          | Supported | CAS locking|
-| Particle  | Photon            | Supported | Interrupt  |
+| CPU / OS   | Boards using CPU  | Status    | Threading  |
+| ---------- | ----------------- | --------- | ---------- |
+| ARM mbed   | STM32, nRF.       | Supported | CAS locking|
+| ESP8266    | Node MCU, Huzzah  | Supported | Interrupt  |
+| ESP32      | Wifi32, Huzzah32  | Supported | CAS locking|
+| SAMD ARM   | MKR, IoT, Zero.   | Supported | Interrupt  |
+| Stm32Duino | STM32F4 boards    | Supported | Interrupt  |
+| AVR        | Uno, Mega Mighty  | Supported | Interrupt  |
+| nRF52840   | Nano BLE          | Supported | CAS locking|
+| Particle   | Photon            | Supported | Interrupt  |
 
 Note: if you are using a bare-metal mbed build (non-RTOS) on platformIO, for the moment please add an extra build flag: `PIO_NEEDS_RTOS_WORKAROUND` as a short term fix while a long term solution is determined. See issue [#17](https://github.com/davetcc/TaskManagerIO/issues/17).