docker-start.sh : can't find diredctory or file

[Streeeech]

If you are using a Dockerfile to build, make sure to use dos2unix on the 'docker-start.sh' before building. The line ending format of this file might cause Docker to not recognize it."

[evonzee]

Added a gitattributes file to address this.

Also, there is now an official docker image, at https://hub.docker.com/r/medeor/starrypy3k. If the team chooses to manage release versions via tags in this repo, they'll also automatically appear on Dockerhub so you can control versioning. For now, there's just a master tag.