Update STM32 Firmware from external flash

Hello,

I am designing an embedded system with these parts:

1. A Low-Power STM32F091RCT6 microcontroller
2. EC25 LTE/GPRS module
3. A 16 Mbit serial flash (W25Q128JV)

After each reset, the microcontroller should check if a new version of firmware is available. If so, the new firmware must be downloaded from server to SPI flash and then programmed to microcontrollers internal flash.

Is it any documentation about this kind of programming?

Thanks in advance.