Docker rails

Hey everyone - I'm submitting this PR to get some early feedback. I'm wondering if the post is clear and has a flow to it. It's quite hard to explain the setup since there is a ton of moving parts just for a basic infrastracture. Also, a lot of the setup is repeated per container so I did my best to skip things that were already mentioned in the post.

Who knew devops could be so complicated? :dancer: 
Yup, this is the code for your Rails app. In the style of docker you want to crush your containers everytime you deploy. It's lightweight and you can spin up containers quickly. In a more complicated setup, I would tag each container with the commit hash and switch nginx to point to the new container. I could leave the container behind to revert back or just redeploy a new container and not have to care about the old container since it might be just as fast to spin up a new container.