docs: Remove outdated mention of `Box<>`.
@@ -19,8 +19,6 @@ use crate::error::LibraryError;
/// Unified message type for MLS messages.
/// /// This is only used internally, externally we use either [`MlsMessageIn`] or
/// [`MlsMessageOut`], depending on the context.
-/// Since the memory footprint can differ considerably between [`VerifiableMlsPlaintext`]
-/// and [`MlsCiphertext`], we use `Box<T>` for more efficient memory allocation.
///
/// ```c
/// // draft-ietf-mls-protocol-16
