XcodeGen/RELEASE.md

The release process for XcodeGen

1. Make sure CHANGELOG.md is up to date:
   • All relevant entries have been added with the PR link and author
   • The new version number is added at the top after Master
   • The Commits link is at the bottom of the release
2. Update the version at the top of Makefile
3. Run make release
4. Push commit and tag to github
5. Create release from tag on Github
6. Run make archive and upload xcodegen.zip to the github release
7. Run make update_brew and push to github