message: Update transitioning url
diff: @@ -193,7 +193,7 @@ consider migrating to the {0} edition by adding `edition = '{0}'` to
  `Cargo.toml` and then rerunning this command; a more detailed transition
  guide can be found at
  - https://rust-lang-nursery.github.io/edition-guide/editions/transitioning.html
  + https://rust-lang-nursery.github.io/edition-guide/editions/transitioning-your-code-to-a-new-edition.html
  ",
  idioms,
  file,
  