add comment on why we are not using a proper middleware

src/http/Server.zig

@@ -33,6 +33,8 @@ pub fn init(
         .port = port,
     }, ctx);
 
+    // We won't use actual middleware for rate limiting here because we only have
+    // a couple routes to protect with rate limiting
     var router = try httpz_server.router(.{});
     router.get("/", handleWeatherRoot, .{});
     router.get("/:location", handleWeatherLocation, .{});