[FEATURE] Add tooltip for course-stats data on landing page

[awpala]

Is your feature request related to a problem? Please describe.
Navigating down the table rows eventually takes the header out of view, at which point it is difficult to intuit/discern the fields (difficulty, workload, overall, number of reviews), given that they are all numeric and within a relatively narrow range.

Describe the solution you'd like
Add tooltip to reveal the data field on hover over the data point (e.g., hovering over entry 3.5 reveals "Difficulty" in the tooltip).

Describe alternatives you've considered
Make the header row sticky (a better alternative, if feasible with MUI)

Additional context
(N/A)