Fix Sample output for "Course grading, part 1" exercise

The content of sample students file is not reflected in sample output
of the exercise. Fix it to have consistent example.

data/part-6/1-reading-files.md

@@ -594,9 +594,9 @@ Please write a program which asks the user for the names of these two files, rea
 
 Student information: **students1.csv**
 Exercises completed: **exercises1.csv**
-pekka peloton 21
-jaana javanainen 27
-liisa virtanen 35
+peter pythons 21
+jean javanese 27
+alice adder 35
 
 </sample-output>