Readme Updates

[diginc]

Need some post-#84 accuracy and improvements to the README.md / documentation and linked scripts. Thoughts so far:

• Review this statement for accuracy: "Upgrading If you try to use pi-hole -up it will fail." since .git folder data is present now.
  • needs updates to any similar statements to strongly suggest the 'docker way' of upgrading, or at least to start from scratch if you have any issues around upgrading.
• A docker hub comment suggested adding --restart=always to the docker run command. 👍
  • Should add to the scripts / docker-compose files too
• Update docker-compose files' schema #86 could fall under this umbrella

Feel free to add any suggestions.

[diginc]

Trying to run the container after docker swarm init fails because of cap_add=NET_ADMIN being broken for swarm. Symptoms are: The container starts, docker userland proxy binds to 53, but DNS on 53 just doesn't work. I'll document as a known issue / FAQ somewhere.

[diginc]

#106 resolves everything but documenting the docker swarm init limitations