Repository Watcher

[eznix86]

I've found another use case for myself, watching other repositories.

example ghcr.io/cloudnative-pg/postgresql I want to watch the latest tags.

So maybe i can have this env

REGISTRY_AUTH_CNPG=ghrc.io
REGISTRY_AUTH_CNPG=<auth>
REGISTRY_WATCH_CNPG=cloudnative-pg/postgresql

It an be comma separated like cloudnative-pg/postgresql, cloudnative-pg/ha,cloudnative-pg/etc,cloudnative-pg/whatever
We can watch last tags amount, maybe have ~N where we can have cloudnative-pg/postgresql~10. Where is is the N is N to amount of tags to watch