message: fix a header in changelog
diff: * `[docs]` Add a documentation note for project `displayName` configuration
  ([#5600](https://github.com/facebook/jest/pull/5600))
  -# Chore & Maintenance
  +### Chore & Maintenance
  * `[docs]` Update automatic mocks documentation
  ([#5630](https://github.com/facebook/jest/pull/5630))
  