doc: update doc test

src/stream/stream/mod.rs

@@ -911,10 +911,10 @@ extension_trait! {
             use async_std::prelude::*;
             use async_std::stream;
 
-            let s = stream::from_iter(vec![-1isize, -2, -3]);
+            let s = stream::from_iter(vec![-3_i32, 0, 1, 5, -10]);
 
             let max = s.clone().max_by_key(|x| x.abs()).await;
-            assert_eq!(max, Some(3));
+            assert_eq!(max, Some(-10));
 
             let max = stream::empty::<isize>().max_by_key(|x| x.abs()).await;
             assert_eq!(max, None);