Merge pull request NixOS#160322 from 06kellyjac/update_readme

README: replace codetriage with normal GH contributors

README.md

@@ -3,7 +3,7 @@
 </p>
 
 <p align="center">
-  <a href="https://www.codetriage.com/nixos/nixpkgs"><img src="https://www.codetriage.com/nixos/nixpkgs/badges/users.svg" alt="Code Triagers badge" /></a>
+  <a href="https://github.com/NixOS/nixpkgs/blob/master/CONTRIBUTING.md"><img src="https://img.shields.io/github/contributors-anon/NixOS/nixpkgs" alt="Contributors badge" /></a>
   <a href="https://opencollective.com/nixos"><img src="https://opencollective.com/nixos/tiers/supporter/badge.svg?label=Supporter&color=brightgreen" alt="Open Collective supporters" /></a>
 </p>