Unmark second block as Rzk to prevent a type error

Because otherwise the identifier `id` would be a duplicate

docs/docs/en/posts/2023-12-24-formatter.rzk.md

@@ -45,9 +45,9 @@ For example, consider the following Rzk code:
 #define id (A : U) (x : A) : A := x
 ```
 which has 11 positions where a new line can be inserted, as shown by these markers:
-```rzk
+```
 #define id (A : U) (x : A) : A := x
---     ^  ^  ^ ^  ^  ^ ^  ^ ^ ^  ^
+       ^  ^  ^ ^  ^  ^ ^  ^ ^ ^  ^
 ```
 This amounts to 2048 combinations that have to be ranked for such a simple line.
 Even the ranking itself is not a straightforward problem to tackle.