config descriptions for custom MRF policies

test/fixtures/modules/good_mrf.ex

@@ -0,0 +1,19 @@
+defmodule Fixtures.Modules.GoodMRF do
+  @behaviour Pleroma.Web.ActivityPub.MRF
+
+  @impl true
+  def filter(a), do: {:ok, a}
+
+  @impl true
+  def describe, do: %{}
+
+  @impl true
+  def config_description do
+    %{
+      key: :good_mrf,
+      related_policy: "Fixtures.Modules.GoodMRF",
+      label: "Good MRF",
+      description: "Some description"
+    }
+  end
+end