Nginx Where in the main nginx conf does it pickup the vhost files?

New to Nginx, so I was reading through their docs, and it looks like the standard way to handle multiple domains on the same server is to configure a single nginx.conf file, with separate server blocks for each domain.

I know Centminmod actually creates separate conf files for each add-on domain... where in the main Nginx config is the include directive that says to include these additional conf files?

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I looked manually and couldn't find anything, and grep didn't turn up anything either, so I assume it's some kind of *.conf line that I'm just not seeing?