Update stainless config

Author: sjmiller609

stainless.yaml

@@ -83,6 +83,7 @@ resources:
       put_in_standby: post /instances/{id}/standby
       restore_from_standby: post /instances/{id}/restore
       stream_logs: get /instances/{id}/logs
+      execute_command: get /instances/{id}/exec
     # Subresources define resources that are nested within another for more powerful
     # logical groupings, e.g. `cards.payments`.
     subresources: