message: Fix link to Regex type in README
diff: @@ -20,7 +20,7 @@ supported.
  Documentation with examples for the various matching functions and iterators
  can be found on the
  -[`Regex` type](https://doc.rust-lang.org/regex/regex/enum.Regex.html).
  +[`Regex` type](https://doc.rust-lang.org/regex/regex/struct.Regex.html).
  ### Usage
  