The content doesn't need to be hosted on LessWrong.
It does need to have changed your beliefs personally. If it changed other people's beliefs, please put this as a comment instead.
Also, the article should be more than simply updating you away from your priors. For example, I'm not interested in things like "learning about a new cause you weren't aware of" but rather in things like "changing your mind about the importance of a cause".
I'm also interested in knowing whether the article was the first time you had come across this point, or it just argued that point better than the previous ones.
Information in other format than articles also work: audio, video, pictures, graph, data table, etc.
This is related to a project idea of tracking belief updates with the goals 1) tracking which information is the most valuable so that more people consume it, and 2) seeing how beliefs evolve (which might be evidence in itself about which beliefs are true; although, I think most, including myself, wouldn't think this was the strongest form of evidence).