nixos: create 'modules/nixos' folder

Let's consolidate all modules under one path, so that NixOS,
home-manager, and nix-darwin (if I ever end up using it down the line)
would go under the same folder.

modules/nixos/services/rss-bridge/default.nix

@@ -0,0 +1,24 @@
+# Get RSS feeds from websites that don't natively have one
+{ config, lib, ... }:
+let
+  cfg = config.my.services.rss-bridge;
+in
+{
+  options.my.services.rss-bridge = {
+    enable = lib.mkEnableOption "RSS-Bridge service";
+  };
+
+  config = lib.mkIf cfg.enable {
+    services.rss-bridge = {
+      enable = true;
+      whitelist = [ "*" ]; # Whitelist all
+      virtualHost = "rss-bridge.${config.networking.domain}";
+    };
+
+    # The service above configures the domain, no need for my wrapper
+    services.nginx.virtualHosts."rss-bridge.${config.networking.domain}" = {
+      forceSSL = true;
+      useACMEHost = config.networking.domain;
+    };
+  };
+}