Although current page is more accurate and WA really included except required steam installscript2.vdf, it still not clearly describe that GOTY never include WA - Gold Edition does. Steam (THQ before Sega) sell it previously as DOW Gold as well (GOTY base game + WA) as Platinum\Complete\Master collection's. Older... oldest versions say that it is excluded from Steam GOTY, wich one is not correct. But now article is good.
GOTY is just updated game +some maps later be included in patches. For Relic games its unclear if every official maps from every re-\special-\edition uncluded in latest updates. Some of them - yes, added in later patches. Probably GOTY is v.1.4 re-release as "lite" version of Gold without addon. Maybe DRM updated\removed. Retail patches 1.4 and 1.41 is still DRM. English International 1.50 or 1.51 remove DRM entirely. None of changelogs describe it. Same happened for Dark Crusade - v.1.2 silently remove disc check. Soulstorm retail 1.2 still have DRM.
No actions required, i guess, to the article itself. Just some additional info if someone look to Discussion.