Add a way to obtain a firmware

[nikitastupin]

Removing the flash chip (e.g. SPI) or MCU from the board for offline analysis and
data extraction (LAST RESORT).
You will need a supported chip programmer for flash storage and/or the
MCU.

Hi,

As far as I know there is a way to extract a firmware from flash chip without removing it from the board (e.g. https://nvisium.com/blog/2019/08/07/extracting-firmware-from-iot-devices.html). I suggest add this way to the guide.

PS I didn't tried it yet by hand but the article is quite convincing.

[scriptingxss]

Great idea! Will include an example walkthrough in the next version.