Add taiki-e/parse-changelog

[abhinav]

parse-changelog is a tool to parse changelog files
and extract sections of them in a scriptable way.
It provides JSON or plain text output which can be fed into other tools.
For example, it can fill in release notes for goreleaser
instead of using commit messages.

# e.g.
goreleaser release \
  --release-notes <(parse-changelog CHANGELOG.md $VERSION)

[alecthomas]

Nice, thanks!