documentation: fix wait_for_endpoint docstring

In #1204, the `wait_for_endpoint` `poll` default was changed from 5 to 30, but the docstring wasn't updated. Update the docstring to  match.

Author: stevenpitts

src/sagemaker/session.py

@@ -4398,7 +4398,7 @@ def wait_for_endpoint(self, endpoint, poll=30):
 
         Args:
             endpoint (str): Name of the ``Endpoint`` to wait for.
-            poll (int): Polling interval in seconds (default: 5).
+            poll (int): Polling interval in seconds (default: 30).
 
         Raises:
             exceptions.CapacityError: If the endpoint creation job fails with CapacityError.