Delete file shares through attachments API

Previously the file was deleted in the file structure of the user is not
expected as the file might not only be related to the card.

Signed-off-by: Julius Härtl <jus@bitgrid.net>

docs/API.md

@@ -959,6 +959,7 @@ For now only `deck_file` is supported as an attachment type.
 
 ### DELETE /boards/{boardId}/stacks/{stackId}/cards/{cardId}/attachments/{attachmentId} - Delete an attachment
 
+    
 #### Request parameters
 
 | Parameter    | Type    | Description                                   |