Suppress type length limit test and note that it is not enforced

Author: compiler-errors

src/attributes/limits.md

@@ -35,14 +35,20 @@ a!{}
 
 ## The `type_length_limit` attribute
 
+> [!NOTE]
+> This limit is only enforced when the nightly `-Zenforce-type-length-limit`
+> flag is active.
+>
+> For more information, see <https://github.com/rust-lang/rust/pull/127670>.
+
 The *`type_length_limit` attribute* limits the maximum number of type
 substitutions made when constructing a concrete type during monomorphization.
 It is applied at the [crate] level, and uses the [_MetaNameValueStr_] syntax
 to set the limit based on the number of type substitutions.
 
 > Note: The default in `rustc` is 1048576.
 
-```rust,compile_fail
+```rust,ignore
 #![type_length_limit = "4"]
 
 fn f<T>(x: T) {}