Update docs/source/custom_forms/index.rst

Co-authored-by: Ethan <[email protected]>

Author: sinisaos

docs/source/custom_forms/index.rst

@@ -47,7 +47,7 @@ Custom forms support ``Enum`` type. Here's a example:
 .. literalinclude:: ../../../piccolo_admin/example/forms/enum.py
 
 .. warning::
-    We need to do the ``Enum`` type conversion from the form data ourselves.
+    We need to do the ``Enum`` type conversion from the form data ourselves as a result of how this feature is implemented. If you don't do this conversion, then the field with be provided as a ``str`` instead of the ``Enum``.
 
 ``FileResponse``
 ----------------