Although Wikipedia articles on unfamiliar topics tend to appear reasonable and coherent, they are actually authored by only a small subset of individuals. Anyone can edit Wikipedia, which gives the impression that the content on Wikipedia is a cumulation of public knowledge, but the content of Wikipedia is actually a reflection of a particular demographic that skews white, American, and male.
Some white people who are bothered by racism do not know what action to take to erode racism. However, one thing that anti-racist white people can do is edit Wikipedia to counteract edits by white supremacists, which tend to remain unchecked and unchallenged.
Welcome to Activism 2.0, where the keyboard is mightier than the pen.