Add Dockerfile howto to README

README.md

@@ -1,2 +1,12 @@
 # site-ffdo
 FF Dortmund (FFDO) specific Gluon configuration
+
+## Using the Dockerfile
+
+See https://docs.docker.com/installation/#installation on how to get Docker.
+
+```
+docker build -t ffdobuild .
+docker run ffdobuild
+```
+