don't use unneeded closure

Co-authored-by: Alphyr <[email protected]>

Author: syvb

library/core/src/iter/traits/iterator.rs

@@ -2646,7 +2646,7 @@ pub trait Iterator {
     /// assert_eq!(
     ///     vec![2.4, f32::NAN, 1.3]
     ///         .into_iter()
-    ///         .reduce(|a, b| f32::min(a, b))
+    ///         .reduce(f32::min)
     ///         .unwrap(),
     ///     1.3
     /// );