zaphyra's git: haumea

add contributing guidelines

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -0,0 +1,29 @@
+# Contributing to Haumea
+
+Unless explicitly stated, all contributions are licensed under
+[MPL-2.0](http://mozilla.org/MPL/2.0), the license used by haumea.
+
+## Making Changes to the API
+
+This doesn't apply to bug fixes.
+
+- Discuss before opening a pull request, so your work doesn't go to waste.
+  Anything from GitHub issues to Matrix discussions are fine.
+- Update documentation accordingly. Everything in `haumea.lib` should to be documented.
+- Add [tests](tests) when necessary.
+  Test your changes with `nix flake check`. Make sure new files are added to git.
+
+## Scope
+
+Haumea only depends on [nixpkgs.lib](https://github.com/nix-community/nixpkgs.lib).
+Features that depend on the rest of [nixpkgs] should not be added.
+However, changes that are specific to, but doesn't depend on [nixpkgs] are allowed.
+
+## Style
+
+- Format all Nix files with [nixpkgs-fmt](https://github.com/nix-community/nixpkgs-fmt).
+- `with` should be avoided unless absolutely necessary,
+  `let inherit` is preferred at almost all times.
+- `rec` attribute sets should be avoid at most times, use `self` or `let-in` instead.
+
+[nixpkgs]: https://github.com/nixos/nixpkgs