Reasoning

Just makes it easier to organize modules with a class instead of a static extension method.

services
	.AddModule<SomeModule>()
	.AddModule<SomeOtherModule>();

public class MyModule : IModule 
{
	public IServiceCollection ConfigureServices(IServiceCollection services) 
	{
		services.AddOtherDependantModule();
		return services;
	}
}