Move over to using release assets

[mjpitz]

Right now, all the artifacts from a release are sent over to a gh-pages branch. It would be better if we could use a release asset format instead of needing to maintain this directory. Right now, our approach needs to use git-lfs in order to handle the artifacts. Using releases would drastically simplify this.

However, we still want to preserve the index.yaml file. We simply want to move the artifact location to be as github assets.

[mjpitz]

This looks really promising: https://github.com/helm/chart-releaser-action