Correct indentation in Chapter 13

book/src/chapter_13.md

@@ -210,8 +210,8 @@ let num_spawns = rng.roll_dice(1, MAX_MONSTERS + 3) + (map_depth - 1) - 3;
 We'll have to change a couple of calls in `main.rs` to pass in the depth:
 ```rust
 for room in map.rooms.iter().skip(1) {
-        spawner::spawn_room(&mut gs.ecs, room, 1);
-    }
+    spawner::spawn_room(&mut gs.ecs, room, 1);
+}
 ```
 
 ```rust
@@ -265,4 +265,4 @@ You now have a dungeon that increases in difficulty as you descend! In the next
 
 Copyright (C) 2019, Herbert Wolverson.
 
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+---