Add Docker image

[inductor]

For someone who just want to try Hermes real quick I think it's nice to have a Docker image officially.

[anubhavmishra]

Thanks for the interest in Hermes! This is on our short-term roadmap as part of some build and release improvements that we were not able to include as part of our initial release. We're attaching the planned-work label to this as something that HashiCorp Labs is going to do.

[trungdlp-wolffun]

You can check my PR @inductor #42