Text not matching code snippets in chapter 57a

https://github.com/amethyst/rustrogueliketutorial/blob/33872fe582f226178436847e1f74eafcbf9c0d1a/book/src/chapter_57a.md?plain=1#L626

There is no `TODO` in the matching code snippet, so this part of the text is likely outdated.
My understanding is that [this section](https://github.com/amethyst/rustrogueliketutorial/blob/33872fe582f226178436847e1f74eafcbf9c0d1a/book/src/chapter_57a.md?plain=1#L785-L802) is now already applied in the snippet and must be removed.