add documents copy email to template preferences

app/views/submitter_mailer/documents_copy_email.html.erb

@@ -1,5 +1,5 @@
-<% if @email_config %>
-  <%= render 'custom_content', content: @email_config.value['body'], submitter: @submitter, sig: @sig %>
+<% if @body.present? %>
+  <%= render 'custom_content', content: @body, submitter: @submitter, sig: @sig %>
 <% else %>
   <p>Hi there,</p>
   <p>Please check the copy of your "<%= @submitter.submission.template.name %>" submission in the email attachments.</p>