added nix build instructions

README.md

@@ -81,6 +81,26 @@ make release-static -j$(nproc)
 
 Make the package: [p2pool-git](https://aur.archlinux.org/packages/p2pool-git/)
 
+### [Nix/NixOS](https://nixos.org)
+
+This is a flake only project. So you have to use [nixUnstable with nix flakes](https://nixos.wiki/wiki/Flakes) to build or install p2pool. 
+The commands below use the new flake specific reference-format, so be sure to also set `ca-refernces` in `--experimental-features`.
+
+Because this project has submodules which are not fixed in _nixUnstable_ yet you have to use the `nix/master` branch:
+```
+nix shell github:nixos/nix/master
+```
+
+Run the binary:
+```
+nix run github:SChernykh/p2pool
+```
+
+Run the binary with arguments:
+```
+nix run github:SChernykh/p2pool -- --help
+```
+
 ### macOS
 
 p2pool binary: