comment fix

src/aes.rs

@@ -181,7 +181,7 @@ fn galois_multiplication(ap: u8, bp: u8) -> u8 {
     p
 }
 
-/// Mix columns data in state, used when encrypting, non-linearity + diffusion.
+/// Mix columns data in state, used when encrypting, diffusion.
 fn mix_columns(state: &mut [[u8; 4]; 4]) {
     for i in 0..4 {
         let mut temp = [0u8; 4];