fixed Schwabish cite

doc/python/horizontal-bar-charts.md

@@ -218,7 +218,7 @@ fig.show()
 ```
 ### Diverging Bar (or Butterfly) Chart with Neutral Column
 
-Diverging bar charts offer two imperfect options for responses that are neither positive nor negative:  omit them, leaving them implicit when the categories add to 100%, as we did above or put them in a separate column, as we do in this example.  Jonathan Schwabish discusses this on page 93 of  _Better Data Visualizations_.
+Diverging bar charts offer two imperfect options for responses that are neither positive nor negative:  omit them, leaving them implicit when the categories add to 100%, as we did above or put them in a separate column, as we do in this example.  Jonathan Schwabish discusses this on page 92-97 of  _Better Data Visualizations_.
 
 ```
 import pandas as pd