add inline comments

Author: danlu1

synapseclient/core/remote_file_storage_wrappers.py

@@ -316,6 +316,7 @@ def progress_callback(*args, **kwargs) -> None:
             progress_bar.update(args[0] - progress_bar.n)
 
         parsedURL = SFTPWrapper._parse_for_sftp(url)
+        # If the port is not specified, it will default to 22
         port_kwargs = {"port": parsedURL.port} if parsedURL.port else {}
         with _retry_pysftp_connection(
             parsedURL.hostname, username=username, password=password, **port_kwargs