Yep that's the directory, lua/autorun/server/motd.lua
In fact, I also have a 'say' command, which basically makes console say something:
timer.Create("motd", 300,0, function() RunConsoleCommand("say", "If you love this server, please add bloodrp.us.to:27018 to favorites") end)
I'm not sure, but I remember reading somewhere that the RunConsolecommand is in the following way: ("command" "parameter") something like that