Generating CHANGELOG.md for reference

Script
$ git log --reverse --pretty="[%s \[%h\]](https://github.com/jeremyf/hydra-capybara-walkthrough/commit/%H)%n%n%w(80,4,4)%b%n" > CHANGELOG.md

This commit was ammended via `git commit --amend` to ensure that
CHANGELOG.md includes this commit message.