doc: secure boot: Explain output of digest_secure_bootloader command
doc: secure boot: Explain output of digest_secure_bootloader command

Mentioned on forum https://esp32.com/viewtopic.php?f=13&t=8162&start=10#p34714

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf