chore: fix broken onboarding link in README (#3732)

# Description

was onboarding this morning to tackle [a quick issue over
here](#3372)

and noticed this link broke in the top level README

https://github.com/noir-lang/noir?tab=readme-ov-file#working-on-this-project

## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[Exceptional Case]** Documentation to be submitted in a separate
PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

Co-authored-by: kevaundray <kevtheappdev@gmail.com>

README.md

@@ -58,7 +58,7 @@ This crate's minimum supported rustc version is 1.71.1.
 
 ## Working on this project
 
-This project uses [Nix](https://nixos.org/) and [direnv](https://direnv.net/) to streamline the development experience. Please follow [our guidelines](https://noir-lang.org/getting_started/nargo_installation/#option-4-compile-from-source) to setup your environment for working on the project.
+This project uses [Nix](https://nixos.org/) and [direnv](https://direnv.net/) to streamline the development experience. Please follow [our guidelines](https://noir-lang.org/getting_started/nargo_installation/#option-3-compile-from-source) to setup your environment for working on the project.
 
 ### Building against a different local/remote version of Barretenberg