v4: Split jupyterlab extensions (#1650)

* Split jupyter extensions back into `plotlywidget` and `jupyterlab-plotly`

The reason for this is that the combined extension made compatibility with nbviewer and voila challenging.

Author: jonmmease

Diff for: README.md

@@ -125,7 +125,10 @@ set NODE_OPTIONS=--max-old-space-size=4096
 # Jupyter widgets extension
 jupyter labextension install @jupyter-widgets/[email protected] --no-build
 
-# FigureWidget support and jupyterlab renderer support
+# FigureWidget support
+jupyter labextension install [email protected] --no-build
+
+# and jupyterlab renderer support
 jupyter labextension install [email protected] --no-build
 
 # JupyterLab chart editor support (optional)