description in the changelog file is
race order is now defined by each race's cvar, set "war3 cvarlist <raceshortname>_raceorder <INTEGER>", you may set it equivalent to your minlevel*100 to order it like that
by default each race increments by 100 , undead = 100, human = 200  (original race register order)

i try write this cvars at war3source.cfg :
war3 undead_minlevel 0
war3 human_minlevel 10
war3 orc_minlevel 20
war3 mage_minlevel 30
......
war3 cvarlist undead_raceorder 100
war3 cvarlist human_raceorder 200
war3 cvarlist orc_raceorder 300
war3 cvarlist mage_raceorder 400
......
what is wrong?

But races interspersed
I have custom races and half of it going at 1st page - Tauren and blademaster, i want 2 put they at a last page, so this cvars don't working. I write it for all 20 races and there is no effect