Simplify first page and remove comments

i Think try F# first sample code should be much simpler, e.g. compare it with rust

https://try.fsharp.org/

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021

we should reduce the information overload and not confuse developers wanting to try F# the first time, also removing accidental complexity of modules, comments and so on, i propose to just have this as first F# program

```fsharp
printfn "hello world"
```

showing up when opening try F# online