Example code and/or online demo

[WardBrian]

I think on the home page it would make sense to include what some Stan code actually looks like. We could also allow users to actually play around with this, either by embedding something like https://brianward.dev/stan-web-demo/ or linking out to https://stan-playground.flatironinstitute.org/

Examples:

• https://ocaml.org/

  

• https://www.python.org/
  

• https://www.haskell.org/

  

• https://gleam.run/
  

[WardBrian]

Here's what that could look like on Stan's homepage (just the minimal example, no demo (yet))

[mitzimorris]

this looks great - let's do it!

cheers,
Mitzi