Add some more content to the empty page state

We think that we need to make it clear what the difference between
uploading a letter and uploading a spreadsheet is, and where you go to
do each.

We get some confusion about uploading being behind the ‘Send’ button on
the template page. There’s some concern that launching the upload page
will increase this confusion, unless we head it off with some messaging.

app/templates/views/jobs/jobs.html

@@ -18,11 +18,17 @@
         {% include 'views/dashboard/_jobs.html' %}
       {% endif %}
       {% if not jobs and not show_scheduled_jobs %}
-        {#
-          `_jobs.html` will show the ‘You have no jobs’ message when
-          passed an empty list of jobs
-        #}
-        {% include 'views/dashboard/_jobs.html' %}
+        <p>
+          You have not uploaded any files yet.
+        </p>
+        {% if current_service.has_permission('upload_letters') %}
+          <p>
+            Upload a letter and Notify will print, pack and post it for you.
+          </p>
+        {% endif %}
+        <p>
+          To upload a list of contact details, first <a class="govuk-link govuk-link--no-visited-state" href="{{ url_for('main.choose_template', service_id=current_service.id) }}">choose a template</a>.
+        </p>
       {% endif %}
       {{ previous_next_navigation(prev_page, next_page) }}
       {% if current_service.can_upload_letters and current_user.has_permissions('send_messages') %}