Update docs for multiple usernames for ACL DELUSER (#1595)

Author: Andrew-Chen-Wang

redis/commands.py

@@ -49,7 +49,7 @@ def acl_cat(self, category=None):
         return self.execute_command('ACL CAT', *pieces)
 
     def acl_deluser(self, *username):
-        "Delete the ACL for the specified ``username``"
+        "Delete the ACL for the specified ``username``s"
         return self.execute_command('ACL DELUSER', *username)
 
     def acl_genpass(self, bits=None):