readme updates

README.md

@@ -29,6 +29,20 @@ provided socket.
 ptouch-api [--config config.toml]
 ```
 
+## Permissions
+
+You'll need to either run `ptouch-api` as root or setup a udev rule to change
+the owner or permissions to allow `ptouch-api` to access the label printer over
+usb.
+
+See [51-ptouch-api.rules](./51-ptouch-api.rules) for an example udev rule,
+placing this into `/etc/udev/rules.d` and adjusting the username as desired
+should give the specified user access to the ptouch printer.
+
+Alternatively you can use
+[51-ptouch-api-everyone.rules](./51-ptouch-api-everyone.rules) to give all users
+on the system access to the label printer.
+
 ## API
 
 - GET `/status`: get printer and tape status for details about the fields.
@@ -71,3 +85,39 @@ The following printers are currently supported
 - PT-D600
 - PT-D610BT
 - PT-P710BT
+
+## NixOs module
+
+For NixOs users, a module is available as a flake that includes everything
+needed run the api.
+
+```nix
+{
+  inputs.ptouch-api.url = "git+ssh://git@codeberg.org/icewind/ptouch-api.git";
+
+  outputs = { self, nixpkgs, ptouch-api }: {
+    nixosConfigurations.my-machine = nixpkgs.lib.nixosSystem {
+      modules =
+        [
+          ptouch-api.nixosModules.default
+          ({config, ...}: {
+            # enable the api service and setup the udev rules
+            services.ptouch-api = {
+              enable = true;
+              # socket = "/path/for/socket/to/listen"; # defaults to /run/ptouch-api/ptouch-api.sock
+            };
+            # expose the api to the outside world
+            services.nginx = {
+              virtualHosts."ptouch.example.com" = {
+                locations."/" = {
+                  proxyPass = "http://unix://${config.services.ptouch-api.socket}";
+                };
+              };
+            };
+          })
+          # ... other configuration ...
+        ];
+    };
+  };
+}
+```