if by "category" you mean "command group" (i.e. /mygroup myaction <args> as opposed to simply /myaction <args>) then those are specified at command creation time, not cog insert time, and while you theoretically could parse the file path of your module (which Python provides to all modules in a variable named __file__) from each individual module and assign commands to groups based on that i think it's more effort than it's worth
#how do you make a cog categorizer?
unreal sparrow
if command groups aren't what you're talking about idk what you mean by "categories"