Docker is sunsetting Free Team organizations

[Paul Spooren]

Hi all,

> 
> we don't mirror it elsewhere.
> 
>> (gitlab/github)
>> docker.io/openwrtorg/imagebuilder
>> docker.io/openwrtorg/sdk
>> docker.io/openwrtorg/rootfs

I’d sunset openwrtorg and only use “openwrt”. 
> 
>> Do we want to apply for "Docker-Sponsored Open Source Program"
>> https://www.docker.com/community/open-source/application/

I’ll write an application.

For the future, I’d like to switch from GitLab CI to GitHub CI, while at it I reworked the Dockerfiles to be simpler, please have a look here:

https://github.com/openwrt/docker/pull/99

Advantage of mirroring to ghcr is that we could speedup the CI a tiny bit.

Paul