Related problem

as already partially tracked in #8450, we need a CONTRIBUTING.md file for developers 😋

cc/ @bobhy
would you like to work on this?

Describe the solution you'd like

there are some scattered parts in the README maybe?

a few things that we might want in the document (not exhaustive at all):

• add a command
• add tests
• use modules (this will come soon with upcoming refactoring)
• use the library to test locally
• run the tests (soon with cargo run -- crates/nu-std/tests.nu as mentionned in stdlib: the tests do not run using the prelude #8809)

Describe alternatives you've considered

No response

Additional context and details

No response