Homepage: add the REPL to the top

[hzoo]

Anyone can help with this but @existentialism made a cool mock of it in photoshop already as well

(can fix the margins between the repl to be smaller)

[existentialism]

I'm lagging a bit, but actually almost done with sort of a working prototype, will post soon, but feedback/thoughts welcome for sure.

Initial idea is that it mimics typing a few examples to show their various transformed output, then will invite the user to experiment more with the full REPL.

[hzoo]

Actually we totally need some example dropdowns in the repl of syntax anyway

EDIT: #59