rename_at and select_at are missing in dplyr help docs

[Brent Brewington]

In this help documentation, http://dplyr.tidyverse.org/reference/select_all.html it only explains how to do select_all / rename_all and select_if / rename_if but it is missing the select_at / rename_at

I'm very familiar with using mutate_at and mutate_if, but I'm not so sure how the rename variant works.

Thanks!