Update doc/python/bar-charts.md

Co-authored-by: Liam Connors <connorsl@tcd.ie>

Author: archmoj

doc/python/bar-charts.md

@@ -304,7 +304,7 @@ fig.update_layout(barmode='stack')
 fig.show()
 ```
 
-### Stacked Bar Chart from aggregating a data frame 
+### Stacked Bar Chart From Aggregating a DataFrame 
 
 Stacked bar charts are a powerful way to present results summarizing categories generated using the Pandas aggregate commands.  DF.agg() which produces a wide format data set with one row for each bar component and a column for each bar, which is the transpose of the orientation of the px.bar wide data frame.  Tranposing and updating the indexes is a somewhat involved option. Here is one straightforward way to aggregate a data set into a summarized form and present the results as a stacked bar.