Need guidance creating new usermod_v2

I’m looking at: usermods/EXAMPLE/usermod_v2_example.cpp: It mentions putting usermod in sketch folder under wled00. Is this usermod.cpp? It mentions registering in usermods_list.cpp but I do not see this file in 0.15. I have my code in usermod.cpp with the REGISTER_USERMOD() function. In platformio.override.ini do I have a flag like: -D myMod, or is it: custom_usermod = myMod? Are the legacy userSetup(), userLoop() functions still needed in my code? I feel like a lot of the documentation is 5 years old at this point.

look at how other usermods do it, there is a difference between 0.15 and 0.16 and for new stuff its recommended to use 0.16