message: Add GH issue number to changelog
diff: @@ -38,7 +38,7 @@ is based on [Keep a Changelog](https://keepachangelog.com).
  - Building executables that link to CAF on 32-bit Linux versions using GCC
  failed due to undefined references to `__atomic_fetch` symbols. Adding a CMake
  dependency for `caf_core` to libatomic gets executables to compile and link as
  - expected.
  + expected (#1153).
  ## [0.18.0-rc.1] - 2020-09-09
  