One place people usually point to is the book "Directing Improv" by Asaf Ronen
https://www.amazon.com/gp/product/B01C664U6K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1\
Other than that, I have taken lots of classes and eventually put my own high school curriculum together based mostly on trial and error over the years.