update readme

README.md

@@ -177,6 +177,17 @@ pkgs.mkNginxServer {
 }
 ```
 
+## development
+
+structure of this repo
+- `default.nix`: the top level NixOS module, which can also be interpreted as a plain nix file
+    outside of NixOS for access to just the nixpkgs overlay. this contains all definitions for
+    packages, library functions, and NixOS modules
+- `lib/`: library functions (ie functions that get added to the overlay) go here
+- `modules/`: NixOS modules go here
+- `pkgs/`: packages that get added to the overlay go here
+- `support/`: WIP support tools (eg generating documentation)
+
 ## licensing
 
 this repository is NOT licensed under a "standard" FOSS license. instead, it uses