v2 docker images - invent a unique repo tag

[qrkourier]

There's no way to distinguish between the more recent unstable release with v1 and v2 releases both targeting the :unstable repo tag.

Invent a new repo tag for v2 or stop pushing v1 to :unstable.

[qrkourier]

Docker images used for Docker and K8S tunneling applications:

• https://hub.docker.com/r/openziti/ziti-host/tags
• https://hub.docker.com/r/openziti/ziti-edge-tunnel/tags