clean up a docstring

Author: VegetarianOrc

temporalio/nexus/_operation_handlers.py

@@ -129,8 +129,7 @@ class CancelWorkflowRunOptions:
     """Options for cancelling the workflow backing a Nexus operation.
 
     These options are built by :py:class:`TemporalNexusOperationHandler` and passed to
-    :py:meth:`TemporalNexusOperationHandler.cancel_workflow_run`. Fields may be added in
-    the future; overrides should consume the fields they need.
+    :py:meth:`TemporalNexusOperationHandler.cancel_workflow_run`.
 
     .. warning::
        This API is experimental and unstable.