Book content contradicts state of the codebase

[PierreGuyot]

rustrogueliketutorial/book/src/chapter_63.md

Line 247 in 33872fe

let content = ecs.fetch::<Map>().tile_content[tile_idx as usize].clone();

At this point in the project, the tile_content field has been removed due to a previous refactor (extracting the /spatial folder).
This loop needs to be replaced with the for_each_tile_content helper.

UPDATE: there seems to be other occurrences of this in the following chapters too.