add newline to make --explain output nicer

Co-authored-by: Alex Macleod <alex@macleod.io>

Author: jonboh

clippy_lints/src/unnecessary_map_on_constructor.rs

@@ -10,6 +10,7 @@ use rustc_span::sym;
 declare_clippy_lint! {
     /// ### What it does
     /// Suggest removing the use of a may (or map_err) method when an Option or Result is being construted.
+    ///
     /// ### Why is this bad?
     /// It introduces unnecessary complexity. In this case the function can be used directly and
     /// construct the Option or Result from the output.