Season 9, Episode 21 "Daring Doubt"

https://derpibooru.org/30642

Synopsis: When another author releases his own version of the events in AK Yearling’s Daring Do books, Rainbow Dash is furious, while Fluttershy is curious to know the truth.

Take a look, it's in a book. Reading Rainbow.
I mean, uhh ... Good morning everyone. Enjoy the episode.