Mention support for C-API types. (#28)

Author: ericsnowcurrently

pep-0520.txt

@@ -183,6 +183,16 @@ so.  Instead, ``__definition_order__`` preserves this one bit of info
 from the class body so that it is universally available.
 
 
+Support for C-API Types
+=======================
+
+Arguably, most C-defined Python types (e.g. built-in, extension modules)
+have a roughly equivalent concept of a definition order. So conceivably
+``__definition_order__`` could be set for such types automatically. This
+PEP does not introduce any such support. However, it does not prohibit
+it either.
+
+
 Compatibility
 =============