Once the Harmony Tutor plugin is stable, add it to the "contrib" plugin index

[regisb]

Tutor plugin indexes are a thing now, and the easiest way for users to manage plugins is with tutor plugins install/upgrade/uninstall pluginname. Once the openedx-k8s-harmony is stable, would you consider adding it to the "contrib" index? I think it would make sense.

[bradenmacdonald]

Suggestion: wait until we have at least one provider using this in production, then publish the plugin on the index.

[gabor-boros]

As OpenCraft is now using the plugin, I think we can add it to TPI.
cc: @bradenmacdonald

[bradenmacdonald]

@gabor-boros Sounds good, let's do that.