docs: Create a markdown-it plugin

docs/gfm-alerts-to-admonitions/default.nix

@@ -0,0 +1,30 @@
+{
+  buildPythonPackage,
+  pytestCheckHook,
+  markdown-it-py,
+  lib,
+  setuptools,
+  pytest-regressions,
+}:
+buildPythonPackage {
+  pname = "gfm-alerts-to-admonitions";
+  version = "0.0";
+  format = "pyproject";
+
+  src = ./.;
+
+  build-system = [ setuptools ];
+  dependencies = [ markdown-it-py ];
+
+  nativeCheckInputs = [
+    pytestCheckHook
+    pytest-regressions
+  ];
+  pythonImportsCheck = [ "gfm_alerts_to_admonitions" ];
+
+  meta = {
+    description = "Transform GFM alerts to nixos-render-docs admonitions";
+    license = lib.licenses.mit;
+    maintainers = [ lib.maintainers.traxys ];
+  };
+}