Fix prune_images docstring

Signed-off-by: Joffrey F <[email protected]>

Author: shin-

docker/api/image.py

@@ -305,8 +305,8 @@ def prune_images(self, filters=None):
         Args:
             filters (dict): Filters to process on the prune list.
                 Available filters:
-                    - dangling (bool):  When set to true (or 1), prune only
-                        unused and untagged images.
+                - dangling (bool):  When set to true (or 1), prune only
+                unused and untagged images.
 
         Returns:
             (dict): A dict containing a list of deleted image IDs and