get this repo up and running

[minrk]

nbviewer.jupyter.org is deployed now on OVHCloud with the config in this repo and the charts defined elsewhere, but there are still steps to take to get to fully automated deploys, or even just where we were before with fully scriptable deploys from one repo.

As we are right now, one must checkout this repo and nbviewer and run:

KUBECONFIG=$PWD/secrets/ovh-kubeconfig.yaml helm upgrade nbviewer ../nbviewer/helm-chart/nbviewer -f config/nbviewer.yaml -f secrets/config/nbviewer.yaml

• document how / distribute git-crypt key to team members (same as mybinder.org) with ssh-vault
• publish helm chart for nbviewer so it can be a dependency, as is done for binderhub/jupyterhub (publish helm chart with chartpress nbviewer#907)
• publish chart for cdn.jupyter.org so it, too can be installed/depended upon from this repo. Alternately, don't publish cdn.jupyter.org and move the chart over here. Likely nobody will ever use it except here, so maybe that makes the most sense
• define invoke commands for doing a helm upgrade script deploy
• set up travis config for doing automatic deployments (similar to, but simpler than mybinder.org-deploy) (deploy from github actions #7)