Change "Updated" column to "Enrolment"

**Is your feature request related to a problem? Please describe.**
The column in the table on Reporting > Students > > All Courses shows "Updated" which implies when they last did something. This is actually the enrolment updated date.

**Describe the solution you'd like**
Rename column to "Enrolment"

**Describe alternatives you've considered**
Maybe "Enrolment Updated" but then it would wrap into two columns.