fix rustdoc warnings

Author: hellow554

src/lib.rs

@@ -2692,7 +2692,6 @@ pub trait Itertools : Iterator {
     /// itertools::assert_equal(oldest_people_first,
     ///                         vec!["Jill", "Jack", "Jane", "John"]);
     /// ```
-    /// ```
     #[cfg(feature = "use_alloc")]
     fn sorted_by_cached_key<K, F>(self, f: F) -> VecIntoIter<Self::Item>
     where

src/ziptuple.rs

@@ -36,6 +36,7 @@ pub struct Zip<T> {
 ///
 /// assert_eq!(results, [0 + 3, 10 + 7, 29, 36]);
 /// ```
+/// [`izip!()`]: crate::izip
 pub fn multizip<T, U>(t: U) -> Zip<T>
     where Zip<T>: From<U>,
           Zip<T>: Iterator,