As far as I know there is no such document.
Litchi has an Online User Guide:
https://flylitchi.com/help
DJI Assistant 2 is a computer program available for Windows & MacOS, it doesn’t run on a phone.
You can use it to check/update the firmware of the drone and controller.
The firmware version of your Mavic Mini does not matter for using Litchi.
Some functions/settings still need the DJI app: