message: doc: add missing closing parenthesis
  Following the style to the nearby links to LICENSE-APACHE
  and LICENSE_MIT, the link to LICENSE-UNICODE was placed
  after an opening parenthesis, but the closing parenthesis was
  missing.
  See also
  PR
diff: @@ -235,4 +235,4 @@ at your option.
  The data in `regex-syntax/src/unicode_tables/` is licensed under the Unicode
  License Agreement
  -([LICENSE-UNICODE](http://www.unicode.org/copyright.html#License).
  +([LICENSE-UNICODE](http://www.unicode.org/copyright.html#License)).
  