stm32/ble: fix tests and add instructions to run example

examples/stm32wb/src/bin/tl_mbox.rs

@@ -11,6 +11,29 @@ use {defmt_rtt as _, panic_probe as _};
 
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {
+    /*
+        How to make this work:
+
+        - Obtain a NUCLEO-STM32WB55 from your preferred supplier.
+        - Download and Install STM32CubeProgrammer.
+        - Download stm32wb5x_FUS_fw.bin, stm32wb5x_BLE_Stack_full_fw.bin, and Release_Notes.html from 
+          gh:STMicroelectronics/STM32CubeWB@2234d97/Projects/STM32WB_Copro_Wireless_Binaries/STM32WB5x 
+        - Open STM32CubeProgrammer
+        - On the right-hand pane, click "firmware upgrade" to upgrade the st-link firmware.
+        - Once complete, click connect to connect to the device.
+        - On the left hand pane, click the RSS signal icon to open "Firmware Upgrade Services".
+        - In the Release_Notes.html, find the memory address that corresponds to your device for the stm32wb5x_FUS_fw.bin file
+        - Select that file, the memory address, "verify download", and then "Firmware Upgrade".
+        - Once complete, in the Release_Notes.html, find the memory address that corresponds to your device for the
+          stm32wb5x_BLE_Stack_full_fw.bin file. It should not be the same memory address.
+        - Select that file, the memory address, "verify download", and then "Firmware Upgrade".
+        - Disconnect from the device. 
+        - In the examples folder for stm32wb, modify the memory.x file to match your target device.
+        - Run this example.
+
+        Note: extended stack versions are not supported at this time. Do not attempt to install a stack with "extended" in the name.
+    */
+
     let p = embassy_stm32::init(Default::default());
     info!("Hello World!");