add a helpful comment to ClassTypeHint.get_parameter_map()

Author: NiklasRosenstein

src/typeapi/typehint.py

@@ -274,6 +274,8 @@ def bases(self) -> "Tuple[Any, ...]":
     def get_parameter_map(self) -> Dict[Any, Any]:
         if not self.args:
             return {}
+        # We need to look at the parameters of the original, un-parameterized type. That's why we can't
+        # use self.parameters.
         return dict(zip(TypeHint(self.type).parameters, self.args))