Stargate the makers of the Stargate 3DS flash cart have posted this update:

Today we release an easy to use, straight to the point, manual for Stargate.
We want to answer regular users (the majority) requests for a guide on how to
use Stargate 3DS key functions.
With our next update – that will add new more advanced features – , we will update
our manual with more details, but we recommend regular users (people who want to
play ROMs in the easiest way possible) to stick to the original manual to enjoy
Stargate 3DS for what is famous and appreciated for: its ease of use!
Click here to download Stargate’s Manual.