security team: add link to security tracker (#1960)

@mweinelt @LeSuisse

Author: fricklerhandwerk

core/src/content/teams/040_security.mdx

@@ -24,7 +24,8 @@ contact:
 
 Security is a priority for the NixOS community. The communication channels on security in the Nix ecosystem are:
 
-- [Discourse announcements on security](https://discourse.nixos.org/c/announcements/security)
+- [Discourse announcements on security](https://discourse.nixos.org/c/announcements/security) for major events
+- [Nixpkgs security tracker](https://tracker.security.nixos.org) for managing information on vulnerabilities in software distributed through Nixpkgs
 - [Security Triage Matrix room](https://matrix.to/#/#security:nixos.org) for triaging issues and coordinating mitigations
 - [Security Discussions Matrix room](https://matrix.to/#/#security-discuss:nixos.org) for discussions around security
 - GitHub Security Advisories on