Translate more views 3rd batch

This merge request adds and/or updates Dutch translations for all the files in config/locales except for the following two files:

1. config/locales/notifications/nl.yml
2. config/locales/views/nl.yml

These two files will be translated in another merge request.

app/views/admin/course_editions/import_projects/overview.html.erb

@@ -63,10 +63,16 @@
                                             approved by you, regardless of their status before the import. After confirmation from the client,
                                             they will be directly set to approved.")]) %>
         </div>
-        <%= f.text_field :subject, required: true, value: params[:subject] ||
-                                                          t('activerecord.attributes.project.copy_to_another_course_edition_notification_subject_template') %>
-        <%= f.text_area :message, rows: 30, required: true, value: params[:message] ||
-                                                                   t('activerecord.attributes.project.copy_to_another_course_edition_notification_message_template') %>
+        <%= f.text_field :subject, required: true,
+                         value: params[:subject] ||
+                                t('activerecord.attributes.project.copy_to_another_course_edition_notification_subject_template', locale: :en) %>
+        <%= f.text_area :message, rows: 30, required: true,
+                        value: params[:message] ||
+                               "#{t('activerecord.attributes.project.copy_to_another_course_edition_notification_message_template_language_below', locale: :nl)}" \
+                                 "\n" \
+                                 "#{t('activerecord.attributes.project.copy_to_another_course_edition_notification_message_template', locale: :en)}" \
+                                 "\n<hr>\n\n" \
+                                 "#{t('activerecord.attributes.project.copy_to_another_course_edition_notification_message_template', locale: :nl)}" %>
 
         <p>You can use the following variables, which will be replaced automatically before sending emails:</p>
         <ul>