Added readme, better image tagging?

.drone.yml

@@ -11,3 +11,6 @@ steps:
       from_secret: password
     repo: fr1nge/mdzk
     auto_tag: true
+    tags:
+      - latest
+      - '1.0'

README.md

@@ -0,0 +1,7 @@
+# mdzk-docker
+
+This is a *very* simple docker container for the
+[mdzk](https://github.com/mdzk-rs/mdzk) zettelkasten publishing framework.
+Created because reinstalling using docker for every automated build was too
+costly.  You can find it on
+[DockerHub](https://hub.docker.com/repository/docker/fr1nge/mdzk/)