numtide cache. for unfree stuff

cachix/numtide.nix

@@ -0,0 +1,13 @@
+
+{
+  nix = {
+    settings = {
+      substituters = [
+        "https://numtide.cachix.org"
+      ];
+      trusted-public-keys = [
+        "numtide.cachix.org-1:2ps1kLBUWjxIneOy1Ik6cQjb41X0iXVXeHigGmycPPE="
+      ];
+    };
+  };
+}