[metrics] Adds some TODOs

system/hosts/mcp/containers/prometheus.nix

@@ -1,6 +1,7 @@
 { config, ... }:
 let inherit (import ./lib.nix config) mkContainer blazestar; in
 {
+  # TODO: Authentication
   virtualisation.oci-containers.containers.prometheus = mkContainer {
     image = "prom/prometheus";
     hostName = "prometheus";