* Download correct artifacts for release channel
Experimental builds should pull artifacts from the
`process_artifacts_experimental` job.
I think instead of two separate CI workflows, a better approach might
be to build stable artifacts to the `build` directory and the
experimental artifacts to a `build_experimental` directory, and
generate both within the same workflow. This would take some work since
lots of things assume the output directory is `build`, but something
to consider in the future.
* Prevent experimental promotion to stable
Adds a check to the `prepare-stable` script to prevent experimental
builds from being published using stable semver versions.
* Improve release script process documentation
* Improved pre-publish instructions/message based on feedback
* Added reminder to attach build artifacts to GitHub release
