[ci skip] Add a demo notebook and tag info

binder/Dockerfile

-FROM jupyter/base-notebook:17aba6048f44
+# Copyright (c) Jupyter Development Team.
\ No newline at end of file
+# Distributed under the terms of the Modified BSD License.
+ARG TAG=17aba6048f44
+FROM jupyter/base-notebook:$TAG
+ENV TAG=$TAG
+COPY README.ipynb .

binder/README.ipynb

+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# jupyter/base-notebook on Binder\n",
+    "\n",
+    "Run the cells below to inspect what's in the [jupyter/base-notebook](https://jupyter-docker-stacks.readthedocs.io/en/latest/using/selecting.html#jupyter-base-notebook) image from the Jupyter Docker Stacks project. \n",
+    "\n",
+    "Click here to open a [JupyterLab](../lab) tab. Click here to open a [Classic Notebook](../notebooks) tab."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import os\n",
+    "print(f'This container is using tag {os.environ[\"TAG\"]} of the jupyter/base-notebook image')"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The notebook server is running as the following user."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "!id"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Here's the contents of that user's home directory, the default notebook directory for the server."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "!ls -al"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Conda is available in the user's path."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "!which conda"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The user has read/write access to the root conda environment."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "!ls -l /opt/conda"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The following packages are conda-installed in the base image to support [Jupyter Notebook](https://github.com/jupyter/notebook), [JupyterLab](https://github.com/jupyterlab/jupyterlab), and their use in [JupyterHub](https://github.com/jupyterhub/jupyterhub) environments (e.g., [MyBinder](http://mybinder.org/))."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "!conda list"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Other images in the [jupyter/docker-stacks project](https://github.com/jupyter/docker-stacks) include additional libraries. See the [Jupyter Docker Stacks documentation](https://jupyter-docker-stacks.readthedocs.io/en/latest/) for full details."
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.7.1"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}