fix doctest

Author: jonboh

clippy_lints/src/unnecessary_map_on_constructor.rs

@@ -16,11 +16,11 @@ declare_clippy_lint! {
     ///
     /// ### Example
     /// ```rust
-    /// Some(4).map(foo)
+    /// Some(4).map(i32::swap_bytes);
     /// ```
     /// Use instead:
     /// ```rust
-    /// Some(foo(4))
+    /// Some(i32::swap_bytes(4));
     /// ```
     #[clippy::version = "1.73.0"]
     pub UNNECESSARY_MAP_ON_CONSTRUCTOR,