docs: fix simple typo, containe -> container (#3015)

There is a small typo in docker/types/services.py.

Should read `container` rather than `containe`.

Signed-off-by: Tim Gates <tim.gates@iress.com>

docker/types/services.py

@@ -436,7 +436,7 @@ def __init__(self, parallelism=0, delay=None, failure_action='continue',
 
 class RollbackConfig(UpdateConfig):
     """
-    Used to specify the way containe rollbacks should be performed by a service
+    Used to specify the way container rollbacks should be performed by a service
 
     Args:
         parallelism (int): Maximum number of tasks to be rolled back in one