#1 mediagoblin-demo in README.md

Hi,

There is a line in README.md:

sudo docker build -t mediagoblin-demo mediagoblin-docker

but I don't know where should be mediagoblin-demo? Looks to me like only mediagoblin-docker is needed.

Oh, now I get it - it's just a tag name!

Docker commands can be confusing, so I would make it more explicit by using: sudo docker build --tag="mediagoblin-demo" mediagoblin-docker

I would also add that it should be run outside the cloned repository, just to be clear.

Another nice improvement would be named instances, like:

sudo docker run -p 8080:80 mediagoblin-docker --name mediagoblin-local