Revert broken change

Author: rylev

src/rust-2021/warnings-promoted-to-error.md

@@ -46,5 +46,4 @@ or `ellipsis_inclusive_range_patterns` and you've not allowed these lints throug
 use of `#![allow()]` or some other mechanism, then there's no need to migrate.
 
 To automatically migrate any crate that uses `...` in patterns or does not use `dyn` with
-trait objects, you can run `cargo fix --edition` you can manually change `...` to `..=` and 
-add `dyn` before trait objects.
+trait objects, you can run `cargo fix --edition`.