docs(extras): add stylix instructions for base16 theme

fixes #133

extras/base16/README.md

@@ -0,0 +1,18 @@
+Base 16 colorschemes can have many applications. If the instructions for your use case are not listed here, please feel free to open an issue or pull request.
+
+## Stylix (NixOS)
+
+To use the cyberdream base16 colorschemes with [Stylix](https://github.com/danth/stylix) add the following to your `configuration.nix`:
+
+```nix
+{ pkgs, ... }:
+
+{
+    stylix.base16Scheme = builtins.fetchurl {
+      url = "https://raw.githubusercontent.com/scottmckendry/cyberdream.nvim/main/extras/base16/cyberdream.yaml";
+      sha256 = "1bfi479g7v5cz41d2s0lbjlqmfzaah68cj1065zzsqksx3n63znf";
+    };
+}
+```
+
+Pay close attention to the `sha256` hash. Especially if you are using the light variant, the hash will be different. NixOS will tell you the correct hash in the error message if you get it wrong.