nix settings: use (github) access tokens

designated for github access tokens to public repos, avoiding rate
limits in conference networks

common/nix-settings.nix

@@ -31,4 +31,9 @@ in
     # use all cores for building
     cores = 0;
   };
+  # TODO: manage access token with sops instead of manual deployment
+  # permissions: needs to be readable by the user invoking nix and root (for nix daemon)
+  nix.extraOptions = ''
+    !include /etc/nix/secrets.conf
+  '';
 }