holy moly we're almost there

doc/integrations/cachix.md

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+# Cachix
+The system will automatically pull a cachix.nix at the root if one exists.
+This is usually created automatically by a `sudo cachix use`. If you're more
+inclined to keep the root clean, you can drop any generated files in the
+`cachix` directory into the `profiles/cachix` directory without further
+modification.
+
+For example, to add your own cache, assuming the template lives in /etc/nixos,
+by simply running `sudo cachix use yourcache`. Then, optionally, move
+`cachix/yourcache.nix` to `profiles/cachix/yourcache.nix`
+
+These caches are only added to the system after a `nixos-rebuild switch`, so it
+is recommended to call `cachix use nrdxp` before the initial deployment, as it
+will save a lot of build time.
+
+In the future, users will be able to skip this step once the ability to define
+the nix.conf within the flake is fully fleshed out upstream.