@g0nz0uk – Yes, as herb says, thats not really needed anymore as it should create it when you set it up in EmulationStation. I’ll try to do a new vid of it.
If you really want to re-create the retroarch file (which will get written to /opt/retropie/configs/all/retroarch-joypads/) you can see the option listed as (3 – Setup, 314 – Configure Input devices for Retroarch)