Add astropy.visualization.quantities_support

[eblur]

Using the function astropy.visualization.quantities_support makes the plotting tasks in this notebook more resilient to changes among matplotlib versions.

See astropy/astropy#8743

[adrn]

One small suggested wording change just before In[11]:
"However, calling the astropy.visualization.quantity_support functions will change the settings on your matplotlib session to better handle astropy Quantity objects:"
to
"However, calling the astropy.visualization.quantity_support() function will change the settings on your matplotlib session to better handle astropy Quantity objects:"

Otherwise looks good!