Added information when plotly does not render in Jupyter notebook.

docs/source/data.rst

@@ -7,7 +7,7 @@ prepare your Datas. We support the following input formats:
 
 1. `Atomic Simulation Environment (ASE) <https://wiki.fysik.dtu.dk/ase/>`_.
 
-We will be adding support to other libraries, soon. 
+We will be adding support to other libraries, soon.
 
 
 ===================
@@ -44,14 +44,14 @@ We also offer a :mod:`ml4chem.data.visualization` module to plot interesting
 graphics about your model, features, or even monitor the progress of the loss
 function and error minimization.
 
-Two backends are supported to plot in ML4Chem: Seaborn and Plotly. 
+Two backends are supported to plot in ML4Chem: Seaborn and Plotly.
 
 An example is shown below::
 
     from ml4chem.data.visualization import plot_atomic_features
-    fig = plot_atomic_features("latent_space.db", 
-                               method="pca", 
-                               dimensions=3, 
+    fig = plot_atomic_features("latent_space.db",
+                               method="pca",
+                               dimensions=3,
                                backend="plotly")
     fig.write_html("latent_example.html")
 
@@ -65,4 +65,7 @@ created.
 To activate plotly in Jupyter or JupyterLab follow the instructions shown in
 `https://plot.ly/python/getting-started/#jupyter-notebook-support <https://plot.ly/python/getting-started/#jupyter-notebook-support>`_
 
+If plotly is not rendering correctly you need to install the jupyter
+extension::
 
+    jupyter labextension install @jupyterlab/plotly-extension