Merge pull request #2879 from andreasfelix/add-nix-topic

add nix topic

Author: kenyonj

topics/nix/index.md

@@ -0,0 +1,14 @@
+---
+aliases: nixos, nixpkgs, nix-lang
+created_by: Eelco Dolstra
+display_name: Nix
+github_url: https://github.com/NixOS
+logo: nix.png
+related: package-manager, language, functional-programming, declarative-language
+released: June 15, 2003
+short_description: Nix, the purely functional package manager.
+topic: nix
+url: https://nixos.org/
+wikipedia_url: https://en.wikipedia.org/wiki/Nix_package_manager
+---
+Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. Please refer to the [Nix manual](https://nixos.org/nix/manual) for more details.