fix: doctests

des/src/block/secret_block.rs

@@ -2,6 +2,7 @@
 ///
 /// Usage:
 /// ```
+/// use des::secret_block;
 /// secret_block! {
 ///     /// docs...
 ///     pub struct Block48(u64, 48, 0x0000_FFFF_FFFF_FFFFu64);

des/src/des.rs

@@ -26,7 +26,7 @@ impl Des {
     ///
     /// ```
     /// use des::Des;
-    /// let des = Des::new(0x1334_5779_9BBC_DFF1u64).expect("Valid key");
+    /// let des = Des::new(0x1334_5779_9BBC_DFF1u64);
     /// ```
     pub fn new(key: impl Into<Key>) -> Self {
         let subkeys = Subkeys::from_key(&key.into());

des/src/key/secret_key.rs

@@ -2,6 +2,7 @@
 ///
 /// Usage:
 /// ```
+/// use des::secret_key;
 /// secret_key! {
 ///     /// docs...
 ///     pub struct Subkey(u64, 48, 0x0000_FFFF_FFFF_FFFFu64);