message: Add change log entry for ko locale
diff: @@ -144,6 +144,8 @@ for the list of changes made since `v2.0.0-alpha.1`.
  - [pl locale was updated for v2](https://github.com/date-fns/date-fns/pull/1140). Thanks to [@Mutisz](https://github.com/Mutisz)!
  +- [ko locale was updated for v2](https://github.com/date-fns/date-fns/pull/1100). Kudos to [@iamssen](https://github.com/iamssen)!
  +
  - New locale-dependent week-numbering year helpers:
  - `getWeek`
  