Edit error message

Co-authored-by: Chad Retz <[email protected]>

Author: dandavison

temporalio/client.py

@@ -460,7 +460,7 @@ async def start_workflow(
         rpc_timeout: Optional[timedelta] = None,
         request_eager_start: bool = False,
         priority: temporalio.common.Priority = temporalio.common.Priority.default,
-        # The following options are deliberately not exposed in overloads
+        # The following options are deliberately not exposed in overloads and are not subject to compatibility expectations
         stack_level: int = 2,
         nexus_completion_callbacks: Sequence[
             temporalio.common.NexusCompletionCallback