We need a way to simplify pull from `quay.io/tinkerbell-actions`, the
location for the reusable actions we release.
https://artifacthub.io/packages/search?kind=4
All the images are proxies via an internal registry. This commit
configures it to look at the images hosted in
`quay.io/tinkerbell-actions` when there is not one in the internal
registry and it proxies.
For example:
$ docker pull 192.168.1.1/tinkerbell-actions/rootio:v1.0.0
v1.0.0: Pulling from tinkerbell-actions/rootio
b5b0f03f0cb8: Pull complete
48742f086697: Pull complete
06d27b65800a: Pull complete
3281556401c6: Pull complete
b94e835dc9fd: Pull complete
Digest: sha256:ec9855556388a690cad2535cf813f69cffa6df24476aedb16b3cdfc0d809492c
Status: Downloaded newer image for 192.168.1.1/tinkerbell-actions/rootio:v1.0.0
192.168.1.1/tinkerbell-actions/rootio:v1.0.0
Signed-off-by: Gianluca Arbezzano <gianarb92@gmail.com>