Add missing icon

[anselmbradford]

Additions

• Adds missing Icon_5_40x40.png.

Testing

• Run standalone and visit http://localhost:8000/paying-for-college2/repay-student-debt/#non-federal:yes:yes and see that step five has an icon image, like steps 1 thru 4.

[coveralls]

Coverage remained the same at 100.0% when pulling d750d05 on ans_add_missing_icon into 09eab0c on master.