Automated image builds for registry

By using CI, builds can be scheduled and the process is unambiguous.

Fixes #2 (closed)

Incidentally, fixed #3 (closed) as part of overall cleanup.

README.md

 # Docker Images [![pipeline status](https://git.ethitter.com/docker/images/badges/master/pipeline.svg)](https://git.ethitter.com/docker/images/commits/master)
 
 A collection of images used with GitLab CI, built using GitLab CI. ♾
+
+## Use
+
+See this project's container registry.