Update README.md

Author: neelsoumya

Diff for: README.md

@@ -46,15 +46,15 @@ OR
 run the script `installer.R` in R Studio.
 
 
-## Extra credit
+## Extra credit exercise
 
 For extra credit, do these problems.
 
 * Download data from
 
 https://github.com/neelsoumya/teaching_reproducible_science_R/blob/main/metagene_score.csv
 
-and train a classifier to predict yes/no (flag_yes_no). This would be a binary classifier. Do this with cross-validation.
+and train a classifier to predict yes/no (flag_yes_no). This would be a binary classifier. Do this with cross-validation. Write your own R code to do this task. You can work in groups. Do this in class.
 
 The data is also available here
 
@@ -64,7 +64,7 @@ https://github.com/neelsoumya/practical_supervised_machine_learning/blob/main/me
 
 https://archive.ics.uci.edu/dataset/2/adult
 
-and train a classifier to predict if income > 50K or < 50K (binary classifier). Do this with cross-validation.
+and train a classifier to predict if income > 50K or < 50K (binary classifier). Do this with cross-validation.  Write your own R code to do this task. You can work in groups. Do this in class.
 
 The data is also available in the `adult` folder here