message: Update changelog
  This is the last commit before we cut the release.
diff: # Release Notes
  -## Unreleased
  +## Platform Version 0.8.3 - 2020-05-25
  * Added builder for fluvio_storage::config::ConfigOption. ([#1076](https://github.com/infinyon/fluvio/pull/1076))
  * Use batch record sending in CLI producer ([#915](https://github.com/infinyon/fluvio/issues/915))
  * Now ResponseApi and RequestApi encoder-decoders are symmetric ([#1075](https://github.com/infinyon/fluvio/issues/1075))
  