minor fixes to the Compas example

[LiFaytheGoblin]

I intent to fix
#79
#80
#81

• I switched the variable names that got mixed up
• I reworded "equally likely to predict" to "equally likely to incorrectly predict"
• I reworded "We can see from the longer bars" to "We can see from the absolute number of occurances given next to a bar"

[lorenh516]

Thanks for these notes Linda, good eye! Two changes look good, but re: #79 group size is a secondary notation. It'd be best to instead highlight what the bars are showing, so "We can see from the longer bars that across 'age_cat', 'sex', and 'race' attributes, the groups COMPAS incorrectly predicts as 'low' or 'medium' risk most often are 25-45, Male, and African American." --> "We can see from the longer bars that across 'age_cat', 'sex', and 'race' attributes, the groups COMPAS incorrectly predicts as 'low' or 'medium' risk most often are Greater than 45, Female, and Other race.". If you make that change I will do another quick pass and then should be able to merge, or if you prefer, you can revert this part and I'll make that edit.

[LiFaytheGoblin]

Thanks for the feedback @lorenh516 and you're welcome. See my updated changes.