Add repl link at top of roc-lang.org

[B-Teague]

Maybe add https://www.roc-lang.org/repl link to top of roc-lang website next to tutorial?

[Anton-4]

Thanks for your input @B-Teague, I've started a discussion on zulip about this.

[B-Teague]

Per zulip chat: playground link that has editor for testing multiple line roc-wasm4 programs.