Docker Image Tag Not Present in README

[MrFlynn]

In the README, it states that you can pull mapcrafter/blockcrafter from Docker Hub. During simple pulls (i.e. without a tag), the Docker Daemon assumes the default tag is latest. A simple pull causes a manifest error because the only tag is master on Docker Hub. See this comment on the Blockcrafter 1.13 update issue for an example.

This is a pretty simple issue to fix. Just specify the tag name in the README or add the tag to the image on Docker Hub with latest.