What does this even mean, anyway? Trending by what metric? Commits? Stars? Watches? Clicks? All of the above? Something else? ???
"What makes repositories or developers trend? We look at a variety of data points including stars, forks, commits, follows, and pageviews, weighting them appropriately. It's not just about total numbers, but also how recently the events happened."
IMO, it would be more useful if Github told us what it means with some specificity. Maybe not every detail, if they want to avoid having people try to game the system... but a synthetic metric that no-one understands the basis of, strikes me as somewhat useless.