Add minimal module doc

publication/lib/field_publication/publications/data.ex

@@ -1,4 +1,13 @@
 defmodule FieldPublication.Publications.Data do
+  @moduledoc """
+  This module handles access to a publication's research database.
+
+  You can retrieve the raw documents or an extended version with the publication's configuration applied. The
+  latter will group the data fields and add translated labels for the different value types, relations etc. (if
+  there are any defined in the configuration). The extended version will be returned as a standardized struct,
+  see the `Document` struct definition below.
+  """
+
   require FieldPublicationWeb.Gettext
 
   alias FieldPublication.{