Doc: Small addition
@@ -94,8 +94,8 @@ pub fn hmac_verify(
///
/// ## Note:
/// Salts should always be generated using a CSPRNG. The `gen_rand_key` function
-/// in `util` can be used for this. The recommended length for a salt is 32 bytes. HKDF is not suitable
-/// for password storage.
+/// in `util` can be used for this. The recommended length for a secret key is the sha functions digest
+/// size in bytes. HKDF is not suitable for password storage.
/// # Usage example:
///
/// ```
