Update readme instructions.

README.md

@@ -10,25 +10,43 @@ An extensible computational environment for Jupyter.
 Jupyter Notebook Extension
 --------------------------
 
+The Jupyter notebook extension source files are in the `jupyterlab/` subdirectory.
+
 ### Prerequisites
 - Jupyter notebook 4.2+
 
+### User installation
+```
+pip install jupyterlab
+jupyter serverextension enable --py jupyterlab
+```
+
+Start up the Jupyter notebook and open a browser to the server's URL with the path `/lab` (e.g., `http://localhost:8888/lab`).
+
+
 ### Developer Installation
+You will need npm (preferably version 5 or later).
 
 ```
 git clone https://github.com/jupyter/jupyterlab.git
-pip install -e jupyterlab
+cd jupyterlab
+npm install
+npm run build
+python setup.py build
+pip install -e .
 jupyter serverextension enable --py jupyterlab
 ```
 
-### Use
-
 Start up the Jupyter notebook, and then open a browser to the server's URL with path `/lab` (e.g., `http://localhost:8888/lab`).
 
+When you make a change to the jupyterlab npm package source files, run `python setup.py build` to rebuild the extension and refresh your browser to see the changes.
+
 
 NPM Package Install
 -------------------
 
+The npm package source files are in the `src/` subdirectory.
+
 **Prerequisites**
 - [node](http://nodejs.org/)
 - [python](https://www.continuum.io/downloads)