Bootloader tutorial not working with certain targets

Hello @samulinyman,

Both, the NUCLEO_F429ZI and NUCLEO_F411RE targets have an

        "bootloader_supported": true,

entry in the mbed-os/targets/targets.json file. But the NUCLEO_F401RE doesn’t. Try to add such also for that target. Maybe it will fix the issue.

Best regards, Zoltan