docs: clarify defer's ephemeral arg (#2053)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Lala Sabathil <[email protected]>

Author: 3 people

discord/interactions.py

@@ -676,6 +676,10 @@ async def defer(self, *, ephemeral: bool = False, invisible: bool = True) -> Non
         - :attr:`InteractionType.component`
         - :attr:`InteractionType.modal_submit`
 
+        .. note::
+            The follow-up response will also be non-ephemeral if the `ephemeral`
+            argument is ``False``, and ephemeral if ``True``.
+
         Parameters
         ----------
         ephemeral: :class:`bool`