kubectl run is being deprecated as a multi-purpose tool.
This PR replaces 'kubectl run' with 'kubectl create deployment'
in most places (except in the very first example, to reduce the
cognitive load; and when we really want a single-shot container).
It also updates the places where we use a 'run' label, since
'kubectl create deployment' uses the 'app' label instead.
NOTE: this hasn't gone through end-to-end testing yet.