Update readme

Author: MarcoDaniels

README.md

@@ -1,3 +1,30 @@
 # Cockpit CMS Proxy
 
 A simple proxy to fetch assets from [Cockpit CMS](https://getcockpit.com/).
+
+---
+
+Install [nix package manager](https://nixos.org/download.html) to manage dependencies.
+
+Start a [nix shell](https://nixos.org/manual/nix/unstable/command-ref/nix-shell.html#options) with
+
+```shell
+nix-shell
+```
+
+Set the environment variables for your Cockpit CMS:
+
+```shell
+export COCKPIT_BASE_URL=https://example.com
+export COCKPIT_API_TOKEN=1234
+export ASSET_PATH_PATTERN=/images/pattern
+export TARGET_HOST=localhost
+export TARGET_PORT=8080
+export PORT=8000
+```
+
+Run the proxy with the command:
+
+```shell
+startDev
+```

shell.nix

@@ -16,9 +16,6 @@ in pkgs.mkShell {
   buildInputs = [
     pkgs.nodejs-18_x
     pkgs.elmPackages.elm
-    pkgs.elmPackages.elm-format
-    pkgs.elmPackages.elm-test
-    pkgs.elm2nix
 
     startDev
   ];