refactor: add comment

Author: pekopekopekopayo

lib/ld-eventsource/client.rb

@@ -99,6 +99,9 @@ class Client
     # @param http_client_options [Hash] (nil)  additional options to pass to
     #   the HTTP client, such as `socket_factory` or `proxy`. These settings will override
     #   the socket factory and proxy settings.
+    # @param async [Boolean] (true)  whether to run the stream in a separate thread
+    #   if true, the stream will be run in a separate thread
+    #   if false, the stream will be run in the current thread
     # @yieldparam [Client] client  the new client instance, before opening the connection
     #
     def initialize(uri,