docs: move nix info to contributing guidelines

.vscode/settings.json

@@ -41,6 +41,7 @@
     "dconf",
     "debuginfo",
     "devedition",
+    "direnv",
     "distro",
     "doctest",
     "doesn",

CONTRIBUTING.md

@@ -31,12 +31,14 @@ When you submit your first pull request, you acknowledge that you agree to the t
 
 ## Development Setup
 
-### Using Nix (Recommended for Linux)
+### Using Nix
 
 If you have [Nix](https://nixos.org/) installed, you can skip the manual setup below and simply run:
 
 ```bash
 nix develop
+# or if you use direnv
+direnv allow
 ```
 
 This will provide Node.js, Rust, and all necessary system libraries.

README.md

@@ -59,16 +59,6 @@ The app can be downloaded from the [releases page](https://github.com/zhom/donut
 
 See [CONTRIBUTING.md](CONTRIBUTING.md).
 
-### Nix Support
-
-For a reproducible development environment (especially on Linux), you can use [Nix](https://nixos.org/):
-
-```bash
-nix develop
-# or if you use direnv
-direnv allow
-```
-
 ## Issues
 
 If you face any problems while using the application, please [open an issue](https://github.com/zhom/donutbrowser/issues).