Suggest Str.concat when trying to concat strings with +

[XDracam]

In the spirit of being beginner friendly: most programmers I know are used to concatenating two strings with +. Roc doesn't need this, but: it would be nice to suggest using Str.concat in the error message to reduce frustration for programmers coming from other languages.

The current output in the installed linux x86-64 binary (nightly from 2024/04/19) is this: (is the crash message intentional?)

» "Hi " + "There"
This Roc code crashed with: "Hit an erroneous type when creating a layout for `4.IdentId(19)`"

── TYPE MISMATCH ───────────────────────────────────────────────────────────────

This 1st argument to + has an unexpected type:

6│      "Hi " + "There"
        ^^^^^

The argument is a string of type:

    Str

But + needs its 1st argument to be:

    Num a

I'd suggest appending a line like Hint: Strings in Roc can be concatenated using Str.concat

(Please tell me if this is not a good contribution)