[ ] make README.md and commit if needed
[ ] make man/pandoc.1 and commit if needed
[ ] Finalize changelog
    tools/changelog-helper.sh
[ ] push release candidate branch rc/VERSION and (if it builds
    successfully) download artifacts
[ ] Use 'make' in macos and windows artifacts to sign code
[ ] make update-website
[ ] make trypandoc
[ ] Tag release in git
[ ] make pandoc-templates
    cd ../pandoc-templates
    git tag REL
    git push
    git push --tags
[ ] Add release on github (use 'make changes_github' and upload files)
[ ] stack upload .
[ ] Announce on pandoc-announce, pandoc-discuss