[Fix] - dedicate act3 to rainbow

[totally-not-frito-lays]

Describe the bug
Currently act3 serves as the "catch-all" for students to try mixing and matching their own functions with other cool and pre-written ones. It seems a little strange to have the other functions that are just hanging out without an explanation as to why they're there.

Expected behavior
I think we'll start migrating towards a model where students pick what patterns they want to learn more about rather than calling a bunch of other functions. More discussion will be handled at our next team meeting.

Proposed fix
We remove the other functions from this one. If students want to use those ones, they can go into the dedicated example / documentation for that.

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Add any other context about the problem here.