Update the foundation board page (#1406)

This syncs it with https://github.com/NixOS/foundation.

src/content/teams/01_foundation-board.mdx

@@ -11,20 +11,22 @@ members:
 - name: Théophane Hufschmitt
  discourse: thufschmitt
  title: Secretary
-- name: Domen Kozar
- discourse: domenkozar
- title: Member
 - name: Jonas Chevalier
  discourse: zimbatm
  title: Member
 - name: Ryan Lahfa
  discourse: RaitoBezarius
  title: Observer
+- name: Janik Haag
+ discourse: Janik
+ title: Observer
 contact:
 - name: Discourse
  href: https://discourse.nixos.org/c/dev/nixos-foundation/47
 - name: Matrix
  href: https://matrix.to/#/#foundation:nixos.org
+- name: GitHub
+ href: https://github.com/NixOS/foundation
 - name: GitHub project board
  href: https://github.com/orgs/NixOS/projects/28
 ---