In this exercise what I'd like you to do is:
1. Update & rename createSubjectControl() to return a FormGroup instead. Inside it, add two formcontrols called subjectName and levelOfExpertise.
2. In the template, bind the formGroupName directive to the index inside the FormArray (line 12) and formControlName directives (lines 15 & 20) to their associated FormControl keys.
Exercise Link: https://stackblitz.com/fork/rxngforms-fa-fg-ex