Publish rootfs files to Releases tab

[UriHerrera]

Apparently it is actually possible to publish ISO files to the Releases tab. We should do that.

See: https://github.com/helloSystem/ISO/blob/9c4f663a4b069c0b38b57fe5b6dbb20e0a522f3d/.cirrus.yml#L43

However, our ISO files are typically huge comparatively, so it's up in the air if GitHub would allow these files there.

[UriHerrera]

Our ISOs are larger files than GitHub allows to in the Releases tab. Instead of ISOs, I'd suggest publishing a rootfs.

[lslvr]

What's your intention in publishing a root filesystem (e.g., using it as a base in future builds)?

[UriHerrera]

What's your intention in publishing a root filesystem (e.g., using it as a base in future builds)?

Yes.