Rename image to be jupyterhub specific

Matches reality!

singleuser-builder/README.md

@@ -1,11 +1,12 @@
 
-# Ubuntu 16.10 Python3 Virtualenv Jupyter Builder
+# JupyterHub singleuser builder
 
 This is a builder image for use with [s2i](https://github.com/openshift/source-to-image). It
-builds a source repository (such as a github repository) into a usable Docker image, without
-the user having to use or understand Docker.
+builds a source repository (such as a github repository) into a docker image that is suitable
+for use with [JupyterHub](http://github.com/jupyterhub/jupyterhub).
 
 It is based off Ubuntu 16.10, and uses [virtualenv](https://pypi.python.org/pypi/virtualenv) to
 provide a custom python3.5 environment.
 
 It looks for a `requirements.txt` file in the source repository, and installs it into the virtualenv.
+It also installs a number of default notebook related modules in there