add comment about what tokens are for

dockworker.py

@@ -55,7 +55,6 @@ def __init__(self,
                  timeout=30,
                  max_workers=64,
                  assert_hostname=False,
-                 use_tokens=False,
                  ):
 
         #kwargs = kwargs_from_env(assert_hostname=False)
@@ -111,6 +110,7 @@ def create_notebook_server(self, base_path, container_name, container_config):
         # Important piece here is the parametrized base_path to let the
         # underlying process know where the proxy is routing it.
         if container_config.use_tokens:
+            # generate token for authenticating first request (requires notebook 4.3)
             token = binascii.hexlify(os.urandom(24)).decode('ascii')
         else:
             token = ''