Use rhysd/changelog-from-release to automate changelog generation

[tyru]

Add a Makefile task to generate CHANGELOG.md file.
rhysd/changelog-from-release can create it from GitHub releases.
(@rhysd said the tool might support fetching draft releases, but it's not confirmed)

Ref

https://twitter.com/Linda_pp/status/1061159664191066112

[tyru]

This tool generates release description from GitHub issues.
https://github.com/feinoujc/gh-search-cli

At release:

1. Generate release description by gh-search-cli
2. Add draft release (by hand?)
3. Generate CHANGELOG.md by changelog-from-release
4. Release