Proposal: Change purpose of docker labels on docker hub

[techknowlogick]

Currently latest on docker hub uses the latest commit from the master branch. This proposal is to add an additional tag (something like dev, devel, or unstable) in place of that, and instead use latest as the latest stable version (at time of creating this repo it is 1.2.3).

[techknowlogick]

Perhaps a first step is to create that second label on docker hub, and then change the purpose of latest. I'd be open to creating that PR.

[techknowlogick]

Closing in favour of #2827