README.md: Update the docker build section

The build instruction needed updating, and I added a reference to the
documentation with the commands for running the container.

diff --git a/README.md b/README.md
index 8b960aaaea2d536e35b3899d61dccf5ae8aee930..a68ef3700bd140e8aa52aec1c3b6d246839ec32b 100644 (file)
--- a/README.md
+++ b/README.md
@@ -71,9 +71,12 @@ guix package -f guix-env.scm:notest
 ### 2. Docker
 
 ```
-docker build -t gnunet .
+# From within the top-level of this repository run:
+docker build -t gnunet -f ./contrib/docker/Dockerfile .
 ```
 
+For more info on using the docker container see [here](contrib/docker/README.md).
+
 
 
 Using GNUnet