clarified conversion of classes with iter method

Author: Jesse Dohmann

docs/docpages/public_api.rst

@@ -79,7 +79,7 @@ Example::
     >>> export({"list": [1, 2, 3], "set": set([1, 2, 2, 4]), "frozenset": frozenset([1, 2, 2, 4]), "dict": dict(a = 2)})
     '<|"list" -> {1, 2, 3}, "set" -> {1, 2, 4}, "frozenset" -> {1, 2, 4}, "dict" -> <|"a" -> 2|>|>'
 
-Any class that has an `__iter__` method is converted to a Wolfram Language :wl:`List`::
+If no converter is defined for a class that has an `__iter__` method, it is converted to a Wolfram Language :wl:`List`::
 
     >>> export((i + 2 for i in range(10)))
     '"{2, 3, 4, 5, 6, 7, 8, 9, 10, 11}"'