Make the default for epoll_instances io_threads/2

src/config.hpp

@@ -20,8 +20,8 @@ struct ServerConfig {
   size_t max_request_size_bytes = 1024 * 1024;
   /// Number of I/O threads for handling connections and network events
   int io_threads = 1;
-  /// Number of epoll instances to reduce epoll_ctl contention (default: 2, max:
-  /// io_threads)
+  /// Number of epoll instances to reduce epoll_ctl contention (default:
+  /// io_threads/2, max: io_threads)
   int epoll_instances = 2;
   /// Event batch size for epoll processing
   int event_batch_size = 32;